Again, I can see where Magos is coming from here, though it's difficult to properly explain without risking upsetting lantz, so I'm relenting for now. Though as GM, it's Elf's call. Whether a sheet is serviceable or not is her decision in the end.
As for the spoiler thing, I honestly think it may be a good idea to post the spoilery stuff in spoiler tags for the purpose of expanding on what's going on, especially since it's separate from your fic stuff. I posted some Fate Extra and CCC spoilers with a warning in Hakuno's sheet, if I recall, for instance (or at least, I think I did. It's hard to explain her backstory without spoiling a few things). It'd possibly help us see them as less OP at least.
And as for the whole "what's going on here?" summary, lantz's sheets seem OP to some of us, but not OP to lantz himself. Magos is explaining (quite bluntly) about how he thinks the sheets are OP, and lantz is replying by saying he doesn't think they are.
My ultimate response is, while I think they're somewhat OP myself, it's ultimately Elf's decision about what's acceptable.