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

Literally. SRD once suggested dividing the schools of magic based on opposites and adding a school of primordial magic.
The only thing that bothers me here is that there are only 3 light spells in Light and Darkness (and a total of 11 spells). Most of the lords have been moved to enchantment.

Interesting, I've already given up on this option :D
I was also thinking about dividing it in such a way that chaos magic becomes fire magic, and suppressing chaos becomes water magic - water magic spells are obtained through perks, as well as the earth-air pair, but here there is a problem with orcs - their inclination towards earth and air makes the following option more logical:
chaos=fireVSsuppression of chaos=earth
and accordingly
summoning=waterVSsuppression of summoning=air
Explicit spells that do not belong to specific elements - elementals, teleport, magic arrow - can be crammed into enchantment again by linking them to certain perks (enchantment, as a form of wielding primordial magic)
Of course, this also looks rather unkempt, but in this way, all the elements are highlighted, and the lack of spells (at least 70 spells are needed for 7 schools) can be balanced with passive perks (various suppressions, elemental lords, penalties similar to storm wind and fog cloud, etc.) - that is, there is a reason to develop magic, but the number of spells per school is smaller (about 7-8) - this will be helped by transferring some of the abilities of units to the schools of magic (I tried, but I couldn't:( ) - that is, to transfer the storm of the thunderlord to air magic, and laying on of hands to water magic (calling it healing)