I rarely hear about them or see their skirts in use, so it's nice to see they are making a name for themselves, or aiming to, in the whitewater world.
I wouldn't expect them or want them to replace the rubber-rand skirts with every crack though. Like latex gaskets, rubber rim tape, etc, rubber-rands eventually do crack eventually. Maybe yours cracked early due to being on the shelf too long before it saw use.
I've used skirts past their wear and tear stage and regret it for sure. I fully expect to get at least a full season out of my IR Lucky Charm; but meanwhile, products like 303 Spray Lube are meant to "stop brittle oxidation and UV decay" on the more expensive or difficult-to-replace things like gaskets and rands.
It does sound like you got some shoddy work done on your IR skirt, regardless. They should've either replaced the whole thing or simply told you "no". Having a skirt fail you in Cripp's New Blow Hole on lower creek isn't fun. I'll never use a skirt that is coming apart at the seams again. To think I used some 'barely-on' skirt for the first half of my first season... Can't remember how many combat rolls I got on it before finally getting a new snapdragon, but I'm glad I never waited to see it come out on me without my permission. It was a flimsy little thing and had almost no play in the bungee-rand.
I'm cool with leaky skirts though; as long as they stay on.
Congrats on finding a new brand you like. Making a customer for life with good customer service is the way to go.