Hi there!
In the current project I am working on, I want to have rooms connected together procedurally. However, if you spawn them in at run time as blue prints it seems to be impossible to give them baked lighting.
It seems like there must be a way to bake the lighting as you want it to be for that particular chunk, then save that lightmap and apply it at run time to the chunk as many times as it appaers - we plan not to have much ability for the chunks to interact with each other, lightingwise. However, I am unsure of how to do that.
a) Is this possible
b) Would it require c++?
Actually have the same problem.
Keep in mind that i’m an unreal engine noob atm. only have about 3 weeks under my belt 
So these suggestions are only things i thought up. haven’t made any of them work successfully yet 
1: easiest yet requires a lot of time. Create a huge non generated level. Like a maze with a ton of doors and stuff. at runtime you then unlock doors and place spawn points procedurally to give the feel that the map is new.
2: You create a custom actor that somehow contains it’s own lightmass data. this would be c++ stuff and i have not yet figured out if this is possible.
3: Level streaming: This is probably the way to go. with this it should be possible to make every room as it’s own level. I think.
4: The Swarm interface. SwarmInterface | Unreal Engine Documentation . This is what is handling baking the light. if you somehow could add this the level loading via c++ you could in theory bake the light at level loading making it possible to do any form of procedually generated stuff. I wouldn’t recommend this tho as the level loading would be extremely long on larger levels.