What steps will reproduce the problem?

No Russian layout. No way to switch between English-Russian. (Apple support this option through CMD-SPACE)

If possible, can you put the table with layouts with keypress codes and key bindings to separate file so it will be possible to fix it manually.

There will be an update to BTstack Keyboard soon which includes a russian layout. All layouts are also in a .plist for manual editing. No ETA, but soon.

Hi. Please try the 1.5 update. It has a russian keyboard layout and allows for character composition. Also, please start using http://btstack.uservoice.com for issues with my BTstack-based products on iOS.