I really like the idea...but I have a couple of points you might want to consider:
1) I've heard A LOT of stories about women meeting "language exchange partners" (usually in the jardines botanico, weirdly) that ended up being exceedingly slimy men looking to pick up foreign women. I think most of them were found on craigslist or Yesba (is that even still going?)
2) If you're meeting a different person each time, and assuming they're fairly normal people, I can imagine the conversations following a similar pattern. I wonder how you could make this interesting for the reader.
3) I found my friends' stories about the exceedingly slimy exchange partners hilarious...This could make for excellent reading. Perhaps not such a great experience for you though. Maybe buy some pepper spray in advance...or a stick.