For example, I'm looking at Yahna's Magick Conferral and Focus Sight. I want to choose to use Magick Conferral when someone with high def/low res is being attacked, True Sight when someone with high Evasion/Evade is being attacked.

However, it's unclear to me if you can even prioritize this way because the "target" of these abilities isn't an enemy, it's your ally.

Then there are the "self boost" abilities like Eagle Eye - it guarantees my attack, sure, but is the only way to make sure it targets a scout/someone with high evasion to make my first attack target them and make it activate on my first attack?

The limited number of Tactics is really limiting when you're trying to customize how someone plays...