While I enjoy a Pole wank as much as the next guy (except maybe Nietzsche

), I have to say I think that map, with a POD in the partitions is a bit too implausible.
The German Polish border is particularily glaring. It seems to be some variation on the Oder-Neisse line, and I frankly have say that makes little sense. I mean, much of those areas were very much majority German, and had been for a long time. I don't see why Poland would want to absorb that many Germans unless it was willing to resort to the ethnic cleansing that occured in OTL.
If I may make a suggestion, move the POD back to the Jageillons. For a time, they were basically the Hapsburgs of eastern europe. If you can get them to survive, it wouldn't be implausible for one of them to eventually inherit Poland, Lithuania, Bohemia, and Hungary.