What things, if any, might need to be taken into account in the design of manual flight controls for supersonic or hypersonic aircraft that wouldn’t need to be taken into account with manual controls for subsonic aircraft?
In the transonic region, control forces may become too high for manual control (e.g. controls froze in WW2 planes diving at high speeds), so supersonic aircraft usually have powered controls rather than manual, cable-operated controls.
You also get CoG shift you have to compensate for. This is often done via a Mach trim system or by automatic fuel transfer.