Hi there, Esther!
Either one of those reservations is perfectly fine. While the show is taking place, the house lights will be lowered throughout the restaurant, and the show soundtrack will be piped through the speakers.
There are two options to actually seeing the fireworks show while dining at the
California Grill: from your table, or from the attached viewing deck.
While you should definitely request a window table in advance of and at check-in, you should be aware that almost every seat in the restaurant will offer a good view of the fireworks through the wall of windows overlooking the Magic Kingdom. Be aware, though, that some of the seats will require you to turn your chair in order to maximize your view. It's not the best idea to head over to the windows, since you'll be blocking those diners whose tables are window-adjacent.
You can also ask a Cast Member if it's permissible to go out on the viewing deck to watch. More often than not, you'll be permitted to go out, but if the weather is inclement or there are other safety concerns, the Cast Member will likely suggest that, for your safety and comfort, you should remain indoors.
You're sure to have an incredible meal experience at the California Grill!
See you later, celebrator,
-Deborah B.