Your question seem devoid of any explanation why tags exists, and your arguments don't seem to directly relate to why tags exist. So lets take a moment to focus on why tags exist.
Tags are a method for getting content in front of a target audience.
Tags are typically used in conjunction with a search mechanism.
However, as can be seen on sites like YouTube, users tend to tag content with irrelevant tags to exploit SEO.
Where to a degree YouTube has reduced the importance of the tagging system.
However since Stack Exchange has a large reliance on tags to reduce the attack vector (and maintenance needed) questions are limited to having 5 tags.
The tagging system is a two-way street.
Firstly the asker is tagging to get answers to the question.
Secondly answerers are filtering tags to get relevant questions.
An asker is likely to want to tag a TypeScript question with JavaScript to maximise the number of relevant answerers the question can reach.
Even if the answerer only knows JavaScript the question is likely to still be relevant as ignoring the TypeScript specific aspects (typically not much of the question) the user can still comment a lot about the underlying JavaScript code.
Now lets focus on one of your arguments:
TypeScript needs to run through a transpiler to run in JavaScript engines.
So TypeScript is not JavaScript.
Additionally Is TypeScript really a superset of JavaScript?
... I have zero interest in TypeScript and the frequency of its appearance with JavaScript makes the point of filtering questions by tag mute.
TypeScript can be seen largely as a library.
Granted one that expands on some of the language semantics.
However many large libraries in JavaScript drastically change the programming style of the language.
For example programming using Vue is a vastly different experience to vanilla JavaScript.
And in my experience a vastly greater difference than TypeScript and JavaScript.
Lets say you don't like TypeScript or Vue the solution is simple.
You filter by [javascript] -[typescript] -[vue.js] tags.
The filter to my eyes does not seem mute and works quite well.
Alternately, is it acceptable to give a JavaScript review to code that is clearly TypeScript (well parts of it) but has the tag JavaScript.
Yes, you are allowed to do so.
As far as I know this can take two forms:
As can be noted the accept next to my answers indicate I have helped the OP.
Answers should primarily be focused on helping the asker.
How you think is best to help, is largely down to you.
Effectively review it as very poor quality JavaScript.
If what you mean is you'll say stuff like; "Your code looks like odd JavaScript, you code doesn't even run in any JavaScript engine." "Maybe you should actually write some JavaScript, not whatever you have posted."
Then please don't do things which aren't helpful.
