[Fuchs2468]

And I don't want do delete my old Kodi 18 database, because it seems that I have to go back to my old Kodi 18 installation when Titan skin doesn't work for me on Kodi 19 :-((

You could make a backup your kodi 18 database.
But you should try a new database created with kodi 19.
This will prevent errors from occurring.  

SHS checks the database entries in the background (to create the fanart backgrounds and more).
That is why errors with SHS in the database are detected earlier.
With skins without SHS, the errors are only detected when you try to call up the faulty database entry.
That is the difference.