I'm not sure if the mod itself is at fault here, but Biomes O' Plenty is listed in the ProjectWorlds world generator list, so making an issue here incase it's a simple fix on this end.

I have no idea where to even start here... I can't say I'm familiar with the plugin and it's hard for me to know if the problem lies in the plugin or in Wasteland. Have you been in contact with the plugin author about this? I'd be happy to get an integration with the plugin, but without any info to go on it's difficult to do so.

https://github.com/trentech/ProjectWorlds/commit/af34eb2a543193605c949bd05c906fb5770ef0f1 found this commit on the ProjectWorlds repo, mentioning BoP and other mod support being added, which tells me support has to be added on his side, not mine.

From what I can tell, it uses a standard Sponge registry, which most likely means there's probably some flag in Forge that will list this as a generator (a "proper" way to include a new world generator, perhaps?).
Strangely, Biomes O' Plenty's codebase has no direct cases of "b_i_o_m_e_s_o_p", which is what is listed in ProjectWorlds' generator list.

Though I must admit, my knowledge is that of a user, not so much a developer.

Interesting, it might be Forge having added new hooks for world generators that Wasteland is not using, instead it's using older methods, I'll have to look a bit deeper into this to find out.