Should Plague be able to see infection progress?

Trying to think of the bad outliers but overall that sounds like a pretty good change.

I'm going to be the black sheep here and say no, for 3ish main reasons. First, I think Plague is plenty strong enough in her current state without the information. Second and third, managing infection is part of a Plague's skill cap; since nearly every action short of walking increases infection, you can have a reasonable idea in your head of how long it will take a survivor to become broken. It's not like Ghost Face, where his power is basically Myers' but for individuals; Survivors don't know Myers' stalk gauge, so why should they know Ghost Face's (not to mention that if survivors could know when they're getting stalked it would make stalking them infinitely harder). It's also not like Trickster, in that there's so much chaos during the flurry of knife throws that it can be difficult to remember how many knives you've hit, and how many more you need to hit especially if the laceration meter has started to decay.

Plague and Sadako's survivor gauges are significantly more lethal than Ghostface's, in addition, neither of them are entirely under the killers control.

Ghostface kinda has to be able to see mark progress. It's entirely governed by your own actions (stalking) and the moment it is triggered, a timer begins, 60 seconds of Expose. Once that timer runs out, you've lost your power. So you need to be able to start it when you need it, so that you can use it within that narrow window of time.

For Plague on the other hand, full infection inflicts the Broken status, and it's indefinite. Meaning there's no way for the survivor to simply 'outlast' the infection. It's also accumulated passively, so you don't have to DO anything to trigger it like GF's stalking. The Plague is under no pressure to capitalise on the infection, and the survivors only way of removing it also gives her power, so it's a win-win, there's no power to lose.

Sadako also has a more lethal power in Condemned. This allows her to eliminate a survivor entirely, and like infection, it doesn't run out. In order for a survivor to lose Condemned, they have to interact with TWO TV's.

Either of them having real time information on the progress of their power for an individual survivor would allow them to do something that their power is not designed for. Precisely time a hit or down for the moment their power takes full effect.

If Plague had this ability, she'd be more similar to Trickster, except that upon completion of her power, the survivor doesn't get a speed boost from the injury. She'd be Trickster, with unlimited knives, with knives that hit survivors automatically when they repair gens, that denies survivors a speed boost on injury.

I don't think it's really necessary. She is already a pretty strong killer and being able to see the infection progress would actually give you a lot of extra information on what survivors are doing and it's not needed.

For example, you would know that:

-A survivor is not doing a gen and not running around somewhere if their infection is not progressing at all (because it doesn't progress while walking or standing still)

-Whether a survivor is interacting with an infected object vs. a non-infected one (interacting with infected objects progresses the infection twice as fast)

Nah. Like you said OP she already has enough going for her.