This.
To fix it, pull on the valve to make sure it's as delaminated as it gets. Smear on urethane glue. I use StormSure. Make sure it doesn't go down into the hole and stick the insides of the bladder together. You could put baking paper or something inside it to protect it with a piece of string going to the main valve so you can pull it out again. Being careful is probably enough.
Press it down nice and flat. I lay the bladder out flat, put the hole of a roll of duct tape over the valve and put a weight on top and leave it overnight.
I've done this for 3 valves and none have failed after repair.
None of the valve delams failed catastrophically out on the water. The bladders got a bit soft but I was able to ride back to the beach. I think the pressure of everything squished up inside the strut and LE tube keeps things down to a slow leak. Once the pressure eases off too much the bladder deflates immediately and can't be reinflated.
Here's a sneaky trick. If you notice your wing getting a bit soft while you're out, you can release the strut clip and the pressure between the strut and LE equalises and makes the wing stiff enough to give you a chance to pump onto the foil and get back to the beach.
PS I exploded a strut after contact between foil and strut in the surf the other day. I repaired the torn strut fabric then had a go at welding the split bladder with a hot iron. After a couple of experimental goes it worked surprisingly well. The bare bladder held some pressure overnight. I re-installed it and pumped it up to 8 psi and it held pressure for 24 hours. I haven't needed to use that wing since I repaired it and I'm a bit reluctant to commit to going out with a potentially dodgy wing in any kind of demanding conditions. The bladder material has a few scary stretch marks, one where it ballooned out of the hole prior to exploding, one near the leading edge (maybe cause by the strut end fold over thing), and stripey stretches near the handle positions.
PPS 20 years kiteboarding and zero delams, zero punctures, one burst bladder on an old kite. A couple of severe canopy tears on a really old kite. 3 years wingdinging, 3 delams and one burst bladder. 3 fairly major canopy tears and one exploded strut.
