Hi,
thank you very much. I am not sure what you mean exactly. There are two things what you may need.
1. https://www.dosbox.com/wiki/KEYB
Unfortunately, this is not extended to UI, but can be set in expert settings. Good way is setup game in UI and then on right side to Main Program is button what generates config to clipboard. Then you can replace expert settings with clipboard content and modify it.
2. Visual look for magic dosbox inbuilt keyboard. By default it has English layout. And only other supported look i russian. It is hardcoded, but in of next updates it will be rewritten and will support other looks.
Keyboard functionality is result of both points. Dosbox must be set to correct keyboard and visual look must support selected language.