RTF is a global modification that replaces all towns in the game.

I would agree with the idea of transforming the "slope" into something related to earth (this is a more appropriate path than reworking "stone skin" into air).
Regarding the idea of changing "dispersion" into a swarm of wasps, then the existing "swarm of wasps" spell could be reworked into a spell from Heroes 7 - "poison spit" or whatever it's called.
In general, the last version of the spellcasting scatter is not ideal, but it is definitely better than it was initially (you had regeneration in fire before - which was completely inappropriate).