Thanks very much! That IS in fact a bug, good catch! :DDD I'll get that fixed!
The invisible being is in fact in Neo Vinclum. He's not easy to find. I don't know if anyone's ever found him.
As for Goddess Lumera, that was a reference to another game I was working on at the time (I like cross-promotional hidden stuff like that XD) but given that that game's production never got far before getting put on hiatus, I may change that dialog. It's not very fitting right now.
Cephiti is fightable but not made to be beaten, more as an easter egg (tho some dedicated people have beaten her). As a blatant homage to a game about dreams, there is a lightbulb you can turn on and off in Neo Vinclum. If you turn the lights off and on repeatedly, there is a chance _something_ will happen (you don't have to leave the room to reset either, but the chance is still very low).
Thanks again for getting so involved in finding all these secrets, and I'm so glad you enjoyed the game! :DDD