High Pass Filter on Gyroscope Data
Uner -

No. You are fooling yourself. If you high-pass as you are doing, any final angle will decay to zero. Try it yourself: step your gyro away from zero on any axis and stay there. Watch what happens to your high-passed output - it will drop back to zero.

If what you are doing is simply to demonstrate that you are reading the gyro correctly, confine your movements to one axis only. Try putting in on a level surface and rotating it horizontally, then tip it in the pitch axis.

If you are going to do anything more involved, you must learn to do angle transformations. I know you don't want to believe this, but until you do your complex movements will continue to make no sense to you.