Getting the author to reply to your github issue would be the best outcome.
Otherwise, if you can get any keymap to work on the Chouchou, you'd be halfway there. Adapting the keymap from another keyboard with the same number of keys should not be too hard. You'd have to learn a bit more about QMK.
The repo has never been updated and the file is missing.
There is the "default" keymap that doesn't use the dlip.h file; you could try it. If it works, you could build your own keymap on top of it.
Another option would be to look for other users' config.
But if you meant the thumb keys should angle down, then I think your only option is to design it yourself with the help of one of the online tools for Dactyl type keyboards.
I am not convinced those are a good ergonomic design however. The thumbs are much stronger for a sideways movement. Like playing the bass guitar.
You didn't explain how you have your Colemak layout setup but I think I understand the problem. I just tried adding Greek to my computer (Corne keyboard, Colemak DH) and it worked as expected.
Can I suggest you try this:
set input to US English in the OS, or a variant with AltGr characters
configure your Colemak layout in VIAL
This way, the computer doesn't even know that you are using Colemak. And it works with all (or most of) the languages!
Very nice boards. I don't think I will ever go to such a low key count.
My main keeb is a Corne with a couple of keys rarely used. So I'm going to give 38 keys a try with a Totem. I think I can deal with 4 keys less but there is also the increased pinky stagger, splay, smaller Choc footprint, flatter keycap profile. Let's see...
Keychron ships from China even if you order on a site in Europe. But it is quick and all charges are already included. I like their keyboards. The V series is very nice for the price.
With the large number of languages you are working with, I think it is worth spending a bit of time creating your own layout. The AltGr layer is where you'll want most of your changes.
On Wayland this is not too difficult to do. On X11, skip the headache and modify the system file.
This is my current Alt layer, mostly for French, with Spanish also being easy enough. My main layer is mostly UK/US alphas. This is on a split 42 keys keyboard but the concept is the same.
If there are some characters that you use very rarely, don't forget you can probably get them with a Compose sequence. For example, I forgot the ß when I redesigned the layer, but I can still get it with Compose + s + s.
I previously switched from ISO to ANSI and it doesn't change much. If you make your own layout it doesn't matter. I think you have an extra key in ISO.
Keycaps? I use blanks. But there are a lot of EU vendors. I can point to a few later.___
Since I have an encoder on my newest keyboard, I try to find some use for it.
On the default layer, it moves the cursor left and right. I'm experimenting with inverting the control mod to move quickly word by word unless I press Ctrl. Pressing the encoder toggles a scrollwheel mode.
On other layers I have the obvious functions
volume
brightness of laptop screen, or of external monitor with Shift (with DDC protocol)
keeb backlight
brightness of indicators (for layers, caps word, special modes...)
It's fun to configure all this but then I find that I don't remember that it's there and don't use it much.
Getting the author to reply to your github issue would be the best outcome.
Otherwise, if you can get any keymap to work on the Chouchou, you'd be halfway there. Adapting the keymap from another keyboard with the same number of keys should not be too hard. You'd have to learn a bit more about QMK.