If you just want to rant and don’t want help, suits yourself…
Your post was erroneous and that was what go me confused.
http://wp.strafverteidiger-cuxhaven.de/ is using Apsen, what does this have to do with testing custom CSS for Xtreme Smart menus ?
http://wp2.strafverteidiger-cuxhaven.de/ is using Xtreme and appear to work fine just using the default threshold (you said worked worse??)
http://wp3.strafverteidiger-cuxhaven.de/ is using Xtreme and does not work, but it is does not seem to be using Smart menus…
It does not look like you have selected use Smart Menus at the top of Main Options > Menus.
My custom CSS clearly says it only works with Smart menus