[2021] Click on a completionist task, get taken to a completely wrong category, have to manually find every task I want to look up. Is there any way to fix this, or is it completely glitched?

We're certainly aware of the issue. It requires implementation of a feature that was descoped from the release. (Along with a lot of other improvements we wanted to make to the achievement interface.)

Both of us are assigned to work exclusively on mobile 'til its release, so I wouldn't expect a resolution until that changes.