I think you just need to require the computer to do the same thing a human does and only look at a specific part of the map at a time. Then switching between fronts will require clicking on the minimap to move the view to a different front, so frequent context switching is naturally penalized by the APM limit.

>You could solve this by coming up with some sort of context-switch effort function but it starts to feel forced.

Doesn't seem too forced to me IMO. Humans have to expend more effort to context switch, so if the goal is to put humans and computers on a level playing field that's something you have to take into account.

no one is even mentioning the role of vision in the game. for a human it's pretty tough to keep track of the minimap and play at the same time. you end up missing a lot of things. imagine something that could monitor both simulataneously.