/assist

I use /assist macro frequently. But I've not used it to target the tank. I use <mo> macros to cast single-target healing spells, so I don't target party members. I usually put a mouse cursor on the tank. If I need to target the tank, I'll just left-click.

Well, I tried this /assist thing yesterday with my Cleric Stance macro and it worked perfectly.

... Well, not so perfectly because I'm not used to it yet. I still have the impulse of cancelling targets and then tap down in the controller twice to move from the mob to the tank, or cancelling target and target the monster when activating Cleric. But it'll get better as soon as my muscular memory knows what to do.

Thanks for the idea, OP.

I put '/target <tt>' in my CS macro. Works perfectly.
It also makes me switch toolbbars from 1 (where my healings spells are) to 2 (all my dots and dps spells).