Mouse over actions should really be officially supported.

[Rongway]

It may take some getting used to but it's something you can learn with muscle memory just like any other controls. I don't ever have to look at function keys to find the right one for the party member because it's automatic for me now.

That you can do it does not negate my statement that it is objectively more difficult than remapping those keys to something closer to your hand's resting position. If a player plays with one hand on the keyboard they should map their keys so that everything is within the sweeping range of their fingers so that they can press them accurately without first spending so much time training themself to press them accurately. For most people this will be the keys to the left of the F4-5TGB diagonal and including it. People with extra long fingers or people who have prior training in piano might comfortably reach the 6YHN diagonal without training.

You can train yourself to press any key on the keyboard accurately if you really want to, but if you map your keys so that they're closer to your resting position, you'll need little or no additional training to press them.

it was so weird not having an actual "Assist" key here. I had to make a macro, lol.

The game calls it "Target the Target of Your Current Target (Assist Target)". I have it bound to T.