As CSMESS has pointed out many times, the possibilities of nerve regrowth are better for those who have had the nerve trunk cut, but ganglia left intact.

I think that the effect of gustatory sweating and tingling is a clue for a possible treatment. We know that for some reason, foods and smells can trigger a sympathetic reaction in the denerved area. If some way could be found to trigger this reaction in appropriate situations, it seems to me this could be effective. I've attempted to suggest this idea to various professionals, and have never gotten so much as a response of any kind.

I wish I could offer something more positive and hopeful, but I just can't. I'm sorry.