I'm about to play with 0.6 version of SE. From what I've seen in 0.6 feature list, core seems are supposed to not allow any other building than core miner build over it. I'll take a closer look at it.
Indeed, inlaind lamps cannot be placed on top of sealed core seams. This seems to be due to way how SE handles crater's collision mask.
For now I'm going to leave it as known incompatibility bug.
