The reason why I'm not using the command card is basically because (as far as I know) there is no way to replace abilities on a command card through triggers. I know you can change the hotkey and icon, but that doesn't really do anything for me because I think it will be detrimental to have a full command card that switches hotkeys around. The way I'm doing it now is just cleaner, and if there is lag I imagine it will be minimal.

From my experience with the editor there is always a way to do something (If you want to put the effort into it). Are all your abilities instant or can they target a point/unit? If they are just instant u can make the each button have a dummy trigger effect that runs a trigger variable (variable so u can change the trigger that runs). Then, u can just change the text, title, and image of the button depending on the abilities they choose. There would be no lag time this way

I should start by saying the method I'm using works well enough and I don't plan on changing it. The only other method I considered was using catalog triggers to construct abilities, but that seemed like more work than its worth. That said:

Except replacing abilities on a command card/adding abilities to units that they don't already have.

The QWER abilities are instant. My left-click spells are target point/unit.

There will be lag, because you're relying on triggers. Using triggers in any way will cause the same trigger lag as what I'm already doing. The only way there wont be lag is if I am actually able to change the abilities on the command card so they are run directly from the command card and not through triggers. Since that isn't possible yet, any method that uses triggers will pretty much be the same (other than using catalogs to build entire abilities, which I don't want to spend time doing).