Looking at Esmerelda Batiste, three optimization problems stand out.
1. She's a Red Court Vampire. That's not very optimal.
2. She's got the totally-useless Cover upgrade for Flesh Mask. Spending Refresh on avoiding Compels is ridiculous. Frankly, Paranet Papers makes a hash of the whole protective-flesh-mask thing.
3. Her Discipline is too low. She can't control her hunger or do anything useful with Domination.
So I say drop Cover, drop Guns (which someone with such deadly claws doesn't need), and raise Discipline. Maybe buy a stunt with that Cover Refresh.
Does that sound about right to y'all?
The talk of spellcasters made me think of this guy I built. Maybe you could take a look at this character and see what you think.
He's fairly powerful. He could be stronger, but looking at the other PCs I wouldn't recommend strengthening him. Then again, that game was stillborn. So...
High Intimidation and Lore in human form matched with physical skills in beast form looks like a good call to me. But I'm not sure Channelling is the best way to go. It's mostly for combat, which overlaps with your beast-form stuff. Ritual or Thaumaturgy might be better. If you did make that change, you could reduce Conviction to boost some other skills.
You can free up a bit of Refresh by attaching Human Form to your Modular Abilities. Would you ever use those powers without using Beast Change first, anyway?
You can also do without Second Set Of Eyes. +1 Alertness, only in one form, only under the right conditions? Seems weak. And not important to your concept.
It's usually best to attach Item of Power to as few Powers as possible, so losing it is less problematic. Alternately, you could make Voss into the IoP for flavour reasons. You won't be using those Powers without Voss around, will you?
I'm not sure if Superb Endurance is pulling its weight in Voss's list. An extra mild consequence isn't that great. With Speed you'll be using Athletics for defence a lot, so maybe raise that? Or go for Superb Stealth and be really sneaky? Or keep your human-form Discipline, so mental attacks are less scary?
Fire is a fine catch, and fitting, but you could get the same rebate from something harder to exploit. Then again, the Catch is already powerful enough without gaming it.