a mirrored version or just a opposite corner or something to make endless blocks of these would be amazing

Thats unfortunately, mh but there isnt anything I can do about this, the incompatibility has to be fixed I guess. Reuploading hundrets of buildings because of a (possible) simple fix is disproportionately, let alone extremly time consuming.

Is this bug only apearing with normal growable buildings turned into rico using the manager, or do you know if a growable that comes with a rico file would also cause this?

There is currently an incompatibility between Theme Manager and the Ploppable RICO mods. If a growable is made into a RICO building, and included in a theme, it prevents it from properly loading. The only solution I've seen for this is to make a copy of the building that isn't included in any theme, and then create a RICO definition.

What do you mean by rico compatible? Every building of mine is rico compatible, its just one click with the rico manager.

I'd love to download these but i can't bring myself to do it without them being rico compatable!