I've gone through 2 in the last 3 months.

Would urethane hold up any better?

Yes. I use a polished Groove Urethane for spares, and as far as I can tell, it's indestructible.

I've had several polyester balls crack/shatter/splinter around the fingers; they seem particularly fragile in that area. One was only a couple of months old; my driller plugged both fingers and a 1/2" buffer around them; filled it and redrilled it. It never cracked thereafter, because, I believe, plug material is urethane, a much more durable material.

So you can plug the finger or thumb, see if your driller can match the colors to your satisfaction or buy a Storm Polar Ice in pearl or solid. They're highly polished urethane balls with a simple pancake core. They should be more durable than most polyester balls.

If super glue is put around the inserts at the coverstock.  Superglue seems to make the cover brittle and subject to cracking.

Super clue could very well be the culprit, but if all your other stuff has inserts then usually a bowler will opt for the same feel with inserts.  Find a urethane ball and polish the heck out of it and you'll have a ball that will outlive you.

Seriously. I have an old Faball Nail I use for spares.  Goes super straight but can hook enough to help kick out double wood if need be.