Passed review with Level Instances still included! Adding directional lights (or any true light casting sources) was not a solution because it’s way too performance costly and damaging to the map, were those building prefabs in the form of Level Instances being placed (and finding and removing those by hand every time Level Instance is placed on the map is getting old quickly). However, this asset pack designed to work only with Lumen, so emissive textures can be used without any additional performance cost if you forgot to remove those. They still mess up lighting inside those prefab buildings at day light conditions and should be removed/turned off, but emission power is low enough so they’re looks passable even if nothing was done:
Overall it’s a not right way to do things (this hack won’t fit for other types of assets, like rocks or other objects), but till some kind of “prefab lighting” implemented in Unreal Editor itself or better system comes in (Scene Graph) - guess this kind of hacky workarounds is the only option…