I will use the default hotkey in instructions below (Mirror F, Mirror Inverse Shift+F, Pipette C).
Now the game looks like this:
If F a blueprint, all buildings will flip up and down.
If Shift+F a blueprint, all buildings will flip left and right.
If C a building then F, it will flip left and right.
If C a building then Shift+F, nothing will be happened.
I think it should be like this:
If F a blueprint, all buildings will flip left and right.
If Shift+F a blueprint, all buildings will flip up and down.
If C a building then F, it will flip left and right.
If C a building then Shift+F, it will flip up and down (especially Stacker).