Thank you, Harald and Hans for your answers on this topic. I have done some (little) further research and I found out, that filenames with characters outside the CP 1250 get converted to a "?" which is not good...
I use Lua file system (lfs) to build a list of available files and then filename lookup is done with the entries I get back. So when a user request cöw.pdf I do a static lookup and return "file does not exist" if it is not in my list. And since lfs does not return the correct file name, the file is not in my list, even though it is on the drive. So even with a mapping (thanks Hans!) I can't do very much. (I will use another external library for the lookup now). Thanks Patrick
