Can I use red wine that has turned as a braising liquid? If not, how else may I use it?

If they were of acceptable quality in the bottle and suffered heat fault, then I would use to deglaze or to throw in a stew. I don't like to waste.

If they were badly faulted in the bottle (wine can suffer a few different faults in the winery and in the bottle) with or without the storage issue, and if I could taste and smell the fault, then I would return to the seller or just discard.

I do cook with wine that I don't drink, but only for deglazing or dishes where the flavour largely disappears except for maybe a small added dimension. When wine is making a star appearance, like for a sauce where wine flavour is key, then that wine must be good in the glass, and while I'm cooking! :-)

If you wouldn't drink it, you really don't want to cook with it. Just chalk it up to experience, and find a good place to store your wines in the summer so they won't cook.

You could take up vinegar making.

I wouldn't!! If they taste bad in the bottle, they will taste bad in your food. Down the drain they go!