I wrote my post too fast, the reticle shouldn't move along a straight line after pitch + roll are applied, but along a different curve. I really need to read up

I wrote my post too fast, the reticle shouldn't move along a straight line after pitch + roll are applied, but along a different curve. I really need to read up on the physics behind it, but it feels too easy to cancel all the rotations along different axes, even when badly upset, compared to other sims (Orbiter, KSP, Simple Rockets)