instead of 03_05_27--Künd.Prüfungsverb.doc

Each file e.g a pdf or word.doc-file can be opened and used without any problems, their content show the German Umlaute, but their names are corrupted.
Servant Salamder contains 2 possible waqys to achieve this. 1: Files -> Convert -> convert or 2) Plugins - Rename - Batch rename
I think, it should be able to convert utf8 back to iso8859-1, but it isn't ? Or what? Could you please help? The codepage850 to iso8859-1 doesn't work ..

My attempts always end with the error: unable to rename file.
Must I use regular expressions - How to achieve a recursive batch renaming for our folders ??
Hubert Köppen