All but the "normal" roof block have an upside-down blockstate.
To describe more in depth the blocks "Lower Roof", "Steep Roof", "Upper Lower Roof" and "Upper Steep Roof" have upside-down blockstates but not "Roof"

Mod versions
Compat Biomes you'll go 1.0
Compat Biomes o' plenty 1.2
Biomes o plenty 17.1.1.162
Biomes you'll go 2.0.0.13

Minecraft 1.19.2
Forge 43.2.3

Fixed