hmm, the tongue thing-could be doing it to evade the action of the nutcracker bit. Maybe a waterford, she would not be able to lean on, could try it, works for mine! Maybe a flash noseband would prevent her opening her mouth enough to get the tongue over? Have her teeth been checked?
Check teeth first.
If the bit is a single jointed one, ponio might not be enjoying the nutcracker action or getting the bit jabbing intot he roof of her mouth. Suggest a waterford or a lozenge bit.
get teeth checked first then get a loose ring snaffle in stead of a normal one they can not lean on something that moves in there month if that dont work then try something else if you start changing bits around willy nilly you may cause your self some probs!