Based on your settings, why bother with a polarizer? Just stop down to F14 and you'll lose a full stop that way - without the bother of screwing on a filter and the potential IQ loss from shooting through additional glass.
The real problem is that, by and large, the static objects in Disney fireworks shows tend to change brightness as the show goes on (this is more true for the castle shows than Illuminations, where there's no actual structure lit up, just the spinning globe which will overavoidably be blurred and lit fountains and some light outlines on buildings), so what may be good for some shots isn't good for others... and of course, sometimes you want a short exposure (if a lot of fireworks are going at once), sometimes you want a long one. IMHO, you are pretty much doomed to occasionally get the static objects over and underexposed unless you both memorize the fireworks show including the lighting of the static objects and make multiple aperture and/or ISO adjustments in order to optimize each individual shot - and I'm certainly not willing to go through that much work. It's over the top enough to swap lenses twice during Illuminations! (From wide to telephoto for globe photos then back to wide.)
I have been tending to go for a slightly smaller aperture lately - F11 usually - which helps keep some of the fireworks from being blown out as much. From there, in Lightroom, I usually do slight "Recovery" to bring back some highlights, usually cool the color slightly (most come through at 4900, I move to closer to 3300 or so), then bump up the saturation, which brings back the color "pop" lost from the white balance change. If there is stuff in the foreground, I'll sometimes add a little fill light, too.