Or maybe unify all those tags under the most common denominator soreness?
I'd say we don't have enough questions about soreness to have 3 different tags for them. I'd also venture to say that we won't likely have many on-topic questions that have need of the tag soreness, as any soreness not related to muscle-soreness probably requires a doctor and is out of scope for this site.
Under soreness we have at least 2 very borderline for being out-of-scope:
- I hurt my back from a deadlift attempt. When can I go back to weight lifting?
- joint problem during workout
The only question which isn't about muscle-soreness of the remaining questions, "How to reduce shoulder soreness during and after squats", is more about bruising type pain than muscle-soreness. Since doms is a subset of muscle-soreness, I think we should probably close the borderline questions, and retag everything to muscle-soreness except the "shoulder soreness" question, and find a creative way to retag it (shoulders + pain).