In his Biographia Literaria, Coleridge refers to a young woman from
Gottingen who spoke in tongues, and whose physician attempted to trace
the true nature of her spoken 'ravings'. This was all pre-1799, before
STC came to town. Who was the woman, who was her physician, and where
would Coleridge have learned/read of the case?

Coleridge himself tells us that he got to know of the case because it
was still being talked about when he arrived in Gottingen.

"A case of this kind occurred in a Catholic town in Germany a year or
two before my arrival at Göttingen, and had not then ceased to be a
frequent subject of conversation."  from Biographia Literaria, Vol. 1,
Chapter 6, lines 2698-2701,
http://www.library.utoronto.ca/utel/rp/criticism/bio_l_6.html

I'm afraid I've not been able to find any information about the
identity of the woman or her physician.