Yandex translate of feedback of CudaText's user post:
I installed a deb package for my system (Mint Cinnamon), but apparently I'm not destined to use the editor. The reason is the same as in Sublime - the editor ignores the current system keyboard layout. It doesn't matter as long as the standard layout is used. But this is not my case…
A bad feeling arose immediately when I read "Better support national keyboards on Linux" on the page at the suggested link
https://wiki.freepascal.org/CudaText#Advantages_over_Sublime_Text_3 Oh, it doesn't bode well for breaking the Unix-way: "A program should do ONE thing, but do it well." There is also the xkb module, which deals with all issues related to keyboard layouts. Don't do "better support keyboards"! Let the specialists working on xkb do this. Keyboard layouts are a much deeper topic than it might seem at first glance.
As I imagine the problem from a technical point of view — it is necessary to process the keycodes proposed by the system (together with the state of the modifiers), and not try to interpret the scancodes received from the keyboard independently. But I could be wrong here.
Switching the layout to the standard one, I was able to experiment a little with the editor.