I think we can†officially†change the flavour from self/others to buff/debuff.

The initial intent was to go with a self / others split because it would allow us to better split the good spells which are mostly buffs. But the only buffs that could go in hexes were the branding spells, and they are not the offending ones. And skalds rely on them even more than crusader did (on more in the book).
Also, thematically, the name hexes is strongly linked with debuffs. The best (only?) name for an "others" school would be enchantment, but it's almost synonymous with charms.

So docs/develop/spells.txt needs to be updated but it's not urgent. Most people already assume that's the way things are.