Attempted to paste a copy of a simple surface+baselayer bp inside a factorismo building and immediately got the following error : https://tinyurl.com/y2nfh7qb

not sure if this is the reason, but as I understand it, they are ment to be placed in the main ground Surface, and factorissimo buildings are a different Surface, wich beltlayer doesnt accept

it is indeed the case that beltlayer does not support factorismo, however it should not crash when such an attempt is made. ive already worked with the author on this but i dont know whether they will simply fix the crash issue or if they will decide to support factorismo.