Q:

1400 year old virgin?

Reading Quran 19:27,28 Christians and Jews encounter something that raises alarms.

Then she brought him to her people, carrying him. They said, "O Mary, you have certainly done a thing unprecedented. O sister of Aaron, your father was not a man of evil, nor was your mother unchaste."

The same alarms were raised in Najran, as we see recorded in Sahih Muslim #5326

When I came to Najran, they (the Christians of Najran) asked me: You read "O sister of Harun" (i.e. Hadrat Maryam) in the Qur'an, whereas Moses was born much before Jesus. When I came back to Allah's Messenger (may peace be upon him) I asked him about that, whereupon he said: The (people of the old age) used to give names (to their persons) after the names of Apostles and pious persons who had gone before them.

The 2 problems the Christians faced in this passage is that...

They understood the Quran saying that Aaron's sister (who lived hundreds of years before the birth of Jesus) was the same person as the Theotokos, making Dei Genetrix about 1400 years old when giving birth to the True God.
They seen that the author of the Quran confused Maryam the sister of Moses with Mary the Mother of God.

The first being problematic to their christian faith, in the understanding that the Light of the world was born of a young woman, but the greatest miracle in fertility & life.
The second being problematic to the legitimacy of the Quran, therefore the legitimacy of the prophetic career of Muhammad.
Luckily Muhammad explains the situation, saying that it was simply the way people were named in the time, simply a metaphor.
Sounds like a closed case, but not yet, there is no evidence (I am able to find) showing in that time (of the Mother of God) where an ordinary person would be named "sister of (pious ancient person)". (Judea preferred)
If there is no evidence, then I can only see 4 situations.

This particular part of the Quran is miraculously the only part of history where this is recorded (600 years after the era).
There is evidence fully satisfying the pending evidence request of many Christians for hundreds of years, making it public and finally settling the centuries long evidence request.
The Hadith quoted is unreliable and the mother of the Lamb of God was truly very old at the birth of the God Incarnate.
Or there is simply an error in the infallible word of God, making Muhammad a fraud.

My question is if there's any evidence backing up the metaphor explained by Muhammad.

A:

The Quranic verse 19:28 is:
يَا أُخْتَ هَارُونَ مَا كَانَ أَبُوكِ امْرَأَ سَوْءٍ وَمَا كَانَتْ أُمُّكِ بَغِيًّا
Ya okhta haroona ma kana abooki imraa sawin wama kanat ommuki baghiyyan 
The Arabic word used here is similar to the Hewbrew word אָחוֹת (achowth), its usage is explained in Gesenius' Hebrew-Chaldee Lexicon as:
Source: Blue Letter Bible, scan on archive.org

Its similar to the Arabic Akhi (brother) which also has cognates in Hebrew where they include tribal relations and similarity of character:
Source: Blue Letter Bible,  Scan on archive.org

From the NT, there seems to be evidence that Mary is related to the descendants of Aaron, brother of Moses, and it could be that the people referred to that:

Luke 1:5 There was in the days of Herod, the king of Judaea, a
  certain priest named Zacharias, of the course of Abia: and his wife
  was of the daughters of Aaron, and her name was Elisabeth.
Luke 1:35 And the angel answered and said unto her, The Holy
  Ghost shall come upon thee, and the power of the Highest shall
  overshadow thee: therefore also that holy thing which shall be born of
  thee shall be called the Son of God.
Luke 1:36 And, behold, thy cousin Elisabeth, she hath also
  conceived a son in her old age: and this is the sixth month with her,
  who was called barren.

I understand that this is a valid interpretation among Christian scholars, though some may disagree with it:
From Elliot's commentary to the Bible for English readers:

Taking the word in its usual sense, it would imply that either the
  father or the mother of Mary had been of the house of Aaron, or that
  the mother of Elizabeth had been of the house of David.
The scanty notices in the Gospels are (1) that she was a “cousin,” or
  more generally a “kinswoman,” of Elizabeth, and may, therefore, have
  been, by her parentage, wholly or in part of the daughters of Aaron.

From Expositor's Greek Testament:

Luke 1:36. καὶ ἰδού, introducing a reference to Elizabeth’s case to
  help Mary’s faith.—συγγενίς, late form for συγγενής (T.R.), a blood
  relation, but of what degree not indicated, suggesting that Mary
  perhaps belonged to the tribe of Levi.—γήρει: Ionic form of dative for
  γήρᾳ (T.R.). Hellenistic Greek was an eclectic language, drawing from
  all dialects as from the poets, turning their poetic expressions to
  the uses of prose.—καλουμένη: Elizabeth is described as one who is
  still being called barren, though six months gone in pregnancy,
  because people have had no means of knowing her state.

From Meyer's NT Commentary:

συγγενίς] The nature of this relationship, which is not at variance
  with John 1:36, although questioned by Schleiermacher and others, is
  wholly unknown. It is, however, possible that Mary was of the stock of
  Levi (so Faustus the Manichean in Augustine, c. Faust. xxiii. 9; and
  recently, Schleiermacher, Schr. d. Luk. p. 26; Hilgenfeld, Ewald,
  Gesch. Chr. p. 177, and others), as the Test. XII. Patr. p. 542 makes
  the Messiah proceed from the stock of Judah (Joseph) and (comp. p.
  546) from the stock of Levi.[25]

Secondly, the Quran contains an account of the life of Mary before Jesus's birth and states that she was dedicated to the Temple and raised under guardianship of the Kohen:

Quran 3:35 [Mention, O Muhammad], when the wife of 'Imran said,
  "My Lord, indeed I have pledged to You what is in my womb, consecrated
  [for Your service], so accept this from me. Indeed, You are the
  Hearing, the Knowing."
Quran 3:36 But when she delivered her, she said, "My Lord, I
  have delivered a female." And Allah was most knowing of what she
  delivered, "And the male is not like the female. And I have named her
  Mary, and I seek refuge for her in You and [for] her descendants from
  Satan, the expelled [from the mercy of Allah ]."
Quran 3:37 So her Lord accepted her with good acceptance and
  caused her to grow in a good manner and put her in the care of
  Zechariah. Every time Zechariah entered upon her in the prayer
  chamber, he found with her provision. He said, "O Mary, from where is
  this [coming] to you?" She said, "It is from Allah . Indeed, Allah
  provides for whom He wills without account."

Although this account is not present in the canonical books of the New Testament (as far as I am aware), its referred to in Catholic and Eastern Orthodox tradition and in some books of the apocrypha.
Wikipedia on the Presentation of Mary:

The account of the Presentation of the Blessed Virgin Mary in the
  Temple is principally based on the Protoevangelium of James, which has
  been dated by historians prior to the year 200 AD. The story relates
  that in thanksgiving for the birth of their daughter, Mary, Joachim
  and Anne decide to consecrate her to God, and bring her, at the age of
  three years, to the temple in Jerusalem. Mary’s presentation in the
  temple draws parallels to that of the prophet Samuel, whose mother
  Hannah, like Anne was also thought to be barren, and who offered her
  child as a gift to God at Shiloh.
Mary remained in the Temple until her twelfth year, at which point
  she was assigned to Joseph as guardian. According to Coptic tradition,
  her father Joachim died when Mary was six years old and her mother
  when Mary was eight. While the story is a legend with no foundation
  in history, the point is to show that even in her childhood Mary was
  completely dedicated to God. It is from this account that arose the
  feast of Mary's Presentation.

So it could be that the people referred to her as a sister of Aaron because of her link to the Priestly order, and her dedication and worship in the Temple, a similar disposition to Aaron.

Tafsir Al Qurtubi narrates the following views present in Islamic tradition on the relation between Aaron and Mary:

فقيل: هو هارون أخو موسى؛ والمراد من كنا نظنها مثل هارون في العبادة
  تأتي بمثل هذا. قيل: على هذا كانت مريم من ولد هارون أخي موسى فنسبت إليه
  بالأخوة لأنها من ولده؛ كما يقال للتميمي: يا أخا تميم، وللعربي يا أخا
  العرب. وقيل: كان لها أخ من أبيها اسمه هارون؛ لأن هذا الاسم كان كثيراً
  في بني إسرائيل تبركاً باسم هارون أخي موسى، وكان أمثل رجل في بني
  إسرائيل
Some said, the Aaron here is  Aaron, the brother of Moses. The meaning
  is that "we took her worship and service (to the Temple) as similar to
  Aaron, then how could she do that?" Some said that she was called
  sister of Aaron because she was of his descendants ... Some said that
  Mary had a (step) brother from a father who was named Aaron, and that
  the name was common among the tribes of Israel because of Aaron's
  piety, and this other Aaron was also well known and exemplary devout person of the Children of Israel.

