Anybody can learn any of the available Powers regardless of their class or background, with the exception of a few that are gated behind the two current soulbinds. 'Catalyst' isn't a Power tag, it's an equipment one and it's not necessary to use Spell-tagged powers, it just makes them more effective by adding certain stats the catalyst possesses (Accuracy and Critical Chance) to spell attacks that don't get applied when using non-Catalyst weapons.
So yes, if you want to teach your Charmer something from the White/Black Mage list or any of the non-classed Powers, nothing is stopping you. Also, props for Black Cauldron love.