Coming up with a new layout is HARD :D
The main constraints of a Corne-style keyboard is that there are much less keys available than what's necessary to write any latin-script language besides English.
One of the main design principles I had was to push all accented characters on an accent layer, breaking with Bépo where almost all of them are directly accessible (but need a full-size keyboard to work), despite some characters like é or à being much more common than Z or K for example.
My main goal was to optimize for French first, English second. Home row is pretty good for both and based on the Bépo layout, except U which seems pretty useless in English. Top row is OK I guess. More skewed towards French, but still rather optimized for both. Bottom row is good for French despite keeping the ZXCV cluster, the right part is not great for English. W and K are pushed to slightly less accessible positions because they are basically never used in French. But they are relatively common in English. So IDK.
I use almost raw bépo layout, with bépo on the OS.
https://github.com/TeXitoi/keyseebee#whats-the-layout
Modifier are, IMHO, bad on the external pinky column, so using it for low used characters are great.
What I really like with bépo is that punctuation is also optimized.