Search for Filenames with Umlaut in MacOS with no results

That Spotlight for searching in WebDAV- or Fuse-Drives under Cryptomator is out of function is clear to me. But I’m irritated, that no file at all with the Umlaute ä, ö or ü is found via the finders search function under MacOS 10.15.7. Can somebody please help me what to do? 1.000 thx.