Couple of things, a spirit level is open to flight forces and doesn't remain level. Bob Hoover demonstration of the roll while pouring a jug of water being an example. If an aircraft cannot maintain altitude it can just descend without stalling.
This thread has just become one giant pocket pissing contest.
Turns at low speed need you to be aware of the aircrafts foibles and handling, no science degree needed, a degree in pedantic's not required either.
Stop this madness.................