Old roof textures only showing outside

I loved that in Adventure Awaits the roof texture showed underneath so you could have proper vaulted ceilings. Unfortunately it seems that whatever makes this happen hasn't been added to the base game and other packs, because my other roof textures are not showing through.

If the texture showing on the underside of roofs was an error, please don't fix it, please add it into the game. Ideally, so we can choose different ones for the outside and inside of the roof and make beautiful vaulted ceilings!