Implement correct toggle of non-default charsets chars like german Umlaute

[fsdafsadfsdsdaf]

Update2: I used Windows and dumped the SAM to obtain the hash of of a password with 3 Umlauts and a ß for testing.

Code:

hashcat.exe -m1000 -a3 --increment --username -o out.txt --backend-ignore-hip -4 charsets\combined\German.hcchr ?4?4?4?4

succeeds to crack the password. A UTF 8 wordlist does as well.
If I create a charfile in UTF8 however, hashcat fails to crack it.