Certain paramaters of the /playanimation command do not work as they should. Some aspects of the commands do work on BDS but don't on normal bedrock worlds. It is a complex command but I understand how it works and I can tell you the following does not work:

The second state string does not work for players under any conditions. Whether the animation is written in full (animation.player.sleeping) or in short (sleeping), does not make a difference. Whether a stopexpression was used, makes no difference. Whether on a server or normal world, makes no difference.

Secondstate parameter does not work at all on normal worlds, but does on BDS. Try using a /playanimation with secondstate, it will (probably) work on BDS but not on normal worlds. This is best illustrated using armourstands and armourstand animations since they dont move.

Molang query is_eating does not seem to work with /playanimation. Other stop expressions do work. I believe query is_blocking does the same as query is_sneaking though.

Another important issue with this command is that the stop expression for players continues to test/run after the first state has ended. So if you use is_on_ground query as the stopexpression, the next time you run an animation with another stopexpression, the initial state will still end if you are on_ground.