Hi Viktoro, and welcome to Tikiwiki Community
No idea, and it doesn't seem an easy question for most normal users, I guess. I would suggest that you attempt to contact a Consultant to solve that problem for you ( I would suggest you contact Sylvie G., since she knows a lot about charsets and languages). Not all of us know that much about different charsets, etc.
Good luck, and I wish you can solve that problem.