By de facto sovereignty, I mean that they control their borders and the land within their borders. I don't mean to make a political statement, but rather acknowledge that despite their lack of recognition they do control this break-away region.
Iraqi Kurdistan is a different situation. They are autonomous, not a breakaway region.
I know it's different, I specified their status. and I have been to Transnistria, so I know how it works there. Also, even the break-away regions behave differently themselves when it comes to their own recognition - f.ex. Transnistria doesn't stamp your passport and on the Trans./Moldova border you don't get an entry stamp of Moldova either (because, well, formally, you are in Moldova), while Karabah gives stamps and with that stamp you can't go to Azerbaijan (my friend was denied entry).
Iraqi Kurdistan is a different situation. They are autonomous, not a breakaway region.