Yeah the FFR commands use what's known as Euler rotation. Honestly, I've never really been able to get a handle on how to use them effectively if you need feedback (such as angles and such), and they seem to frequently give really off values, which yield things like oscillating angle values (on account of another axis completely being flipped).
It caught me off guard the first few times. I usually just stick with ROTATE OBJECT based commands, they seem to do the trick.
"Time...LINE??? Time isn't made out of lines...it is made out of circles. That is why clocks are round!" -Caboose