Hello Tobias,
There are apparently enlargers with a parallelogram guide. However, I don’t know of any by name, and I don’t think Meopta makes any either. Such devices are likely to be found only in quite high price ranges, though.
You can view further Meopta enlargers, amongst other things, at
http://www.meopta.cz/history/.
As far as I am aware, colour filter sets for the Opemus devices are only available from the Opemus 5 onwards.
Best regards
Volker S.