Hmm, unfortunately the Python plugin API is incomplete here, and does not expose the flipping states. They are not part of the tile, but part of the cell, and the Cell class is lacking a bunch of methods in tiledbinding.py:
Alright, I’ve added access to those attributes with the following change:
Note that they are not added as functions, but should probably be accessed like tileLayer.cellAt(x,y).flippedHorizontally, etc. In case of writing a reader plugin, it should be possible to assign to them as well.
The additions will be included in a possible Tiled 1.1.6 release, and I’ll make sure to merge it to master before publishing the next development snapshot.