I propose we synonym charmed to mind-control.
This would be fairly uncontroversial at another time (possibly debatable still, but not quite so controversial), but at the moment there are a few things I think are causing misunderstanding that I'll work through before giving the reasoning for the proposal. Skip to the end for just the rational for the proposal.
Preamble: Tags are for subjects, not game terms
Tags are for question subjects, which are usually expressed in the natural language most likely to be found by searchers.
Tags aren't meant for technical game terms directly. The only time a technical term gets its own tag is when the subject of enough questions is that technical term and there are enough of those questions to need them to be gathered together under one tag. Even then, it gets a tag not because it's a technical term, but because it has risen to the level of a subject here, in its own right.
I bring this up because there is an active misconception that something being a technical term in D&D is relevant to tagging, although it isn't. The only thing that's relevant is what topics questions are about, and being or not being a technical term is an incidental attribute of a tag, not a core reason to exist.
Why does that matter? Because the relationship in D&D between charmed and mind control (or mind-affecting abilities) has been cited, but is irrelevant when we are considering the relationship between charmed and mind-control (or mind-affecting.
In sum, we don't care what “charmed” means rules-wise in D&D — whether it's a Condition or a sub-category of Mind Affecting Spells or whatever system-specific details — because that has no bearing on how we manage our question topic categorisation.
Some examples of tagging subjects, as they arise in questions
Tags should cover the question's topic directly rather than indirectly:
If Jame Bond 007 has a skill to cause a charming effect on an NPC (and IIRC my old copy, it does), then it almost certainly falls under skills rather than charmed. That latter tag was created to cover mostly the strong, compulsion type of charm that is usually magical or supernatural; its tag description doesn't lend it to using (e.g.) skillscharmed whenever Bond seduces a henchman or a D&D bard uses Performance to mundanely sway a crowd. Such a question shouldn't have charmed in the first place, so shouldn't have mind-control either even if they're made synonyms.
If, for example, a Fate game has ways to charm people, it's almost certainly not going to be a question about how charm effects work — it's going to be about how Aspects work in that situation. Tagging such a question with charmed or mind-control is out of place, because the question isn't about those except incidentally — it's about how Aspect rules work in Fate, and would take aspects.
Although I can imagine charmed being added to a subset of such Fate questions, on most it would not be doing useful categorisation work, since charm-type effects is not a useful division of expertise in Fate. It certainly wouldn't belong on all Fate questions about fictional situations involving charm magic.
This hypothetical is here as an example of a technical term rising to the level of RPG.se first-class Subject: it is often the main topic of a question, and those are useful to gather together, so it got a tag due to that subject-ness, regardless of its technical-term-ness.
Similarly, we have the illusions tag because how illusions work became a subject needing categorisation. The tag doesn't represent the School of Illusion, it represents the larger concept of illusions themselves, and there are possible questions about the School that shouldn't have the tag due to not actually being about illusions themselves.
An example question I can think of that is about the School of Illusion but not illusions is one that asks about designer reasons why an AD&D 2nd ed. Illusionist doesn't get access to Necromancy. Such a question would actually have adnd-2ewizardnecromancydesigner-reasons, and not illusions!
Proposal: synonym charmed to mind-control, and worry about other tag subjects as they come up
In common parlance, magical or supernatural charm is a form of mind control, and charmed is, in intent and in current tagging practice, only really for that kind of non-social, supernatural charming effect. For non-supernatural mind control charming, we have sufficient tags already to categorise those questions, so we don't need to account for them here.
Since concepts that have become widely-applicable question subjects are what we tag with, we should tag accordingly. Since that kind of charm is covered by the concept of mind control, and since there has been some mention that people have looked for a mind-control tag (I have too!), it makes sense to make charmed a synonym of mind-control.
If there are other adjacent topics that need tags, or we for some reason really need to subdivide questions between “hard” mind control and “soft” mind control, those needs will assert themselves and become clear as we move forward. We can take care of those at that later time.