re:   I checked the fluid reservoir on top of the instrument panel and
it is way over full, right up to the top. I plan on siphoning some out
tomorrow (with a turkey baster), but I was wondering what, if any,
problems this might have caused or would cause if I didn't bring it
back down to the correct level

The only damage an overfilled brake master cylinder can cause is the
damage caused by spilled brake fluid.