Hello,

It's been a year now that I've been working on an optimized cyrillic Colemak-based layout. So, I wanted to share my results with you.

Here is how I approached the problem of fitting all 30 bg letters on a standard us keyboard. First, I generated several layouts trying to optimize each of them:
1) based on letter frequency (in Bulgarian; not Russian, English, or another language)
2) by minimizing the amount of disruption to the base Colemak layout
3) using several training text (fiction, non-fiction, wikipedia and newspaper articles) in Bulgarian to do a more detailed analysis using the website: http://patorjk.com/keyboard-layout-analyzer/#/main  (The analysis was a bit of a pain as the website does not accept user-based layouts, so I had to map cyrillic letters in my test layouts to latin letters on existing layouts, and so on, and so on ...)
4) using common sense

I ended up with several more or less equivalent layouts according to the subjective and objective measures above. I tested them for a month or so, and ended up with the following "best" layout, which I have been using for almost a year now (touch typing of course) without any wrist injuries! ;)

I hope you find it useful!