First, i am using the GCAM-mod.
Aquilonian inverted sloped wedged roofs cannot been attached via bottom. I only tested these, because right now i must level thralls´n stuff 
Also, they (ISWRs) only snap to foundations and walls.
Btw. this is a complete new ability of transfering stability, which is weird. Normally tiles provide stability via the sides, not the corner. It´s like if you could attach wedged (flat) roofs with the corner. It would be more coherent if Inverted Sloped Wedged Roofs could be attached by their ascending sides! 
