I have test times an encoder equipped with blue LEDs. If now even the holes in the front panel are made slightly larger, so the knob covers the hole only slightly, something blue light should leak at the sides. Here are two pics …

FPGM are the programmable potentiometers, right? It’s good to have them on the left side, as it’s good for live-modulation while playing. And most people will play a keyboard with their right hand - so the left hand is free for tweaking the knobs. I also like the diagonal arrangement of those.

I think its better to have the midi/on leds on the top and the LFOs on the side (as it is on the last image). Is there any reason why there are only LFO leds and no ENV leds? What’s the function of the on led? Does it show that the synth is powered on? That’s redundant because the screen tells the same already. I would prefer if the on led showed an active note (like a gate led)

I would move the volume knob a little more to the side. Otherwise it might “block” the buttons next to it. You will usually operate the RND,W/S buttons with the right hand, coming from the right side. The height of the Volume knob could make it cumbersome to operate the knobs.

Maybe you might want to re-think the layout a little bit. Currently it’s all very crammed in the center, you could spread it out on the panel a bit more making it more pleasant to use at the same time. Having the buttons on the left of the volume knob is also probably not so great, since you might bump into the pot when trying to push the top two. Last thing: try to align some controls, having things aligned will make the panel look tidier.

+1
The Blofeld uses a quite similar theme: You select a page with the buttons. You can then scroll to additional pages with the page select encoder. Or put differently: The pages are arranged like:
OSC-VCF-ENV-LFO-AMP
where each of these has multiple sub pages for the multiple oscillators, and each of those has in turn a few pages of settings. e.g.
OSC1-1, OSC1-2, OSC1-3, OSC2-1, OSC2-2, OSC2-3, VCF1-1, VCF1-2,VCF2-1, …

Scrolling the encoder scrolls through all the pages, ony by one. Pressing the ENV Button selects page ENV1-1. Pressing the ENV button again selects page ENV2-1

Its much easier to use than to explain. Basically its like a book with multiple pages and shortcut buttons to take you to the chapter beginnings.

SAVE could be realised by pressing a button combination. it could be indicated on the panel by linking two buttons with a line and writing SAVE next to it.