Yeah I don't anybody likes getting blasted with load music the first thing when opening up the game. So I say the sooner you find a possible fix the better. I admittedly don't have any dev experience, so I can't offer any suggestions even though I'd like too.
And as for balance, I'm of the opinion that the less nerfing a game can get away with the better. So if you think you can buff Vepar without nerfing Gremory too much if at all without wrecking the game balance, I say go for that. Vepar's special sting skill felt a little on the weak side, so maybe buff that a bit?
Also bats and sleeping guards aren't the toughest enemies, so it makes sense Gremory's high damage would cut though them. Some magic resistant enemies would probably show off her glass canon-ness better.