Having recently purchased a new California, I have zero regrets.....
I haven't looked under the roof-seal, but IMO, it's a cosmetic issue for now, and hopefully a fix will present itself before it becomes a serious issue.... I'll take a look, as the warranty period draws to a close.
Memories and enjoyment in life are whats important.... Yes, VW should react, and give its customers peace of mind, but big corporations are often slow to react, then litigation concerns kick-in when they try to, and everyone rightly scornes them for going quiet, and trying to cover-their-ass.... But they're all the same at the end of the day, the grass may appear greener with other brands, but not always the case once put to the test.
The VW Camper, is somewhat in a niche of its own, and it is a very much in-demmand product. If you don't buy one, someone else will, and they will get all the enjoyment you should have had also. No product is perfect however, VW have broad-shoulders..... And will have to deal with it. Yes, they have been slow to learn, and sometimes shown apparent contempt for their customers.... But their reputation, is at stake, and they will have to address the issue in-time.
Above is just my view of things, as they stand..... Ultimately, you will have to decide, retirement can either include Cali ownership, or I'm sure you'll find an alternative product to spend your money on. Either way, make the best of your retirement, and try not to dwell on life's imperfections too much, is all I can say.