This is more dramatic than "foreign accent syndrome", although the story is short, the source suspect, and even without those two de-weighting considerations I would highly doubt it's real. I would put money down that we're going to find one of the following:
1) It's exaggerated, and at most she has some form of foreign accent syndrome.
2) The girl spoke German before she was in a coma.
Ask Language Log: "Strange Writing"
4 hours ago