Uninherited timing sections must be the same in every difficulty of the mapset. That is, each section must have the same BPM and offset in each difficulty. Furthermore, there must not be extra or missing uninherited sections in any difficulty. A song's timing doesn't change between difficulties, so there's no sense in having different uninherited sections per difficulty.Basically, some maps might have some GOOD reasons to have different BPMs between difficulties. An example is Big Black, that had some problems because Taiko's BPM was 180 because of some glitches that would happen if the BPM was 360; while the standard difficulty was 360BPM.
I suggest to just add this small exception to the rule.