From my experiences with sealing, I would seal it, without hesitation. The crackling is pretty well along and I wouldn't want to lose any more paint. The downside is you will have to make sure the glass stays in a climate controlled environment from now on. I have had them peel in extreme cold conditions after sealing, it's a real thing.

I use painter's tape that I very carefully cut to fit with about a 1/16" boarder left on the windows so the sealer can cover the edges. Sometimes there will be an unsightly edge left afterward. I very carefully ease that with the tip of an exacto knife. Also prep is important. I try to clean the windows before sealing, best done with a light touch of a Q-tip. This stuff is all very delicate work, but work preserving a decent original glass IMO. The best part of this process is you can do touch ups after without risk of removing any more paint with common hobby acrylics. I wear magnifying headgear and backlight the glass on a simple table of a milk crate with a drop light inside. If the color doesn't look good, you can easily wipe if off and start again.

Common sense here......don't disturb flaking paint other than a light pass with a sealer. I am now using Rustoleum's version since the real Triple Thick is very hard to find locally. After you get the flakes to set, then you can hit it again. I would rather leave some dirt, than loose more paint. Leaving it alone completely-if already flaking will only lose more every time you shake the game/move it.

Not in my local (Kingston) one, nor Micheal's anymore. Try the Rustoleum stuff. Seems just as good to me and much cheaper.