Arcanus Continuum modifies the base pehkui values, so any mod that changes those such as an origins mod/datapack, or size changing device, don't work. (in my case Touhou Origins)

This can be partially mitigated by making spell size changes persistent, so it is not always setting the player back to a scale of 1, but the scale spell shapes as well as dispell still resets the scale when used on a player.

One solution I'd suggest is having Arcanus implement a modifier into pehkui, so that when a scale is modified it changes the modifier values instead