It looks like you have the right of it by checking the Mirrored property. IIRC this will allow you to find those elements that have one flip setting, but not both. Mirroring on both axes is an equivalent transformation to rotating 180°.
If you know the specific relative orientation you want to set, it might make more sense to just set the properties you need (flipHand, flipFacing, rotation). If you know the configuration you want all the elements to have, I probably wouldn’t worry about filtering out ‘correct’ elements unless you have a huge amount to process.
If you’re looking for Nodes that access flipHand and flipFacing, look in Clockwork or archi-lab