Terminals vs concourses matters for presentation in application. A passenger going to an airport only needs to look at terminals first, then the concourses after entering. Making many `=terminal` inside the airport makes them less useful.

A wiki definition isn't absolute, and it may be using common language, or describing common simple case of having 1 terminal and 1 concourse only. `building=` already means it is a "building". Repeating this definition in `=terminal` is redundant. The emphasis on "building" may also refer to how you shouldn't draw the `=terminal` to cover the apron, only the passenger facility.

1. Why is it "invalid"? There's no "not accepted", especially for such a specialized topic. It is used by a few already. As asked there, JFK does have concourse A and B in Terminal 4. That remains unsolved.
2,3. I have already considered backward compatibility. The presence of `building=` is on those 2 `aeroway=concourse` should be enough. There is no necessity to enforce a one-to-one correspondence between `=terminal` and `building=` . For example, if Sky Bridge is considered as a `building:part=bridge` , can main T1 and NSC be 1 `building=` ? The definition of a `building=` may vary. The main problem here is both MFC and NSC are named "concourse", and marked as T1. That should be consistent with the 5 concourses in main T1.
4. There is no such thing as you must use "approved" features osm.wiki/Any_tags_you_like
5. You know you can discuss on my changeset first? Saying "fix incorrect" without checking doesn't help. You say "and it seems to make no sense to me personally. " , that's why " This doesn't automatically mean you should remove them. They may have been added for a specific purpose. If you think they might be junk then try to contact the author. ".

T1 is one terminal. MFC and NSC are 2 concourses of it. This follows the name, obviously.
2. `site=terminal` is invalid. What "terminal"? `aeroway=terminal` should be used Don't use `=site` either when `=multipolygon` is fine. Then it has the meaning as T1 being a `=terminal` covering all of these concourses. It is inconsistent to have some concourses being `=terminal` . and others simply a `building:part=` . This doesn't follow how they are named as T1 either. Different `building=` doesn't matter.

Actually Ft Lauderdale, and Richmond. In any case, please follow osm.wiki/Good_practice#Don't_remove_tags_that_you_don't_understand

Please read osm.wiki/Talk:Aeroways#Aeroway=concourse . This is in use in JFK. This is not a `building:part=` . It's meaningless to use it without different `building:levels=` etc 3D attributes.

Please don't upload test edits to a live public database. This is considered vandalism.

Please don't change minibus stops to franchised bus stops. Create a new point.

Please don't remove the `landuse=highway`

1. Please don't add `tourism=aquarium` inside a `=theme_park`
2. Please don't use `tourism=attraction` with `attraction=` facilities

Please don't delete then recreate basically the same thing. This has no difference.

That's why it's better to list them out on wiki instead of Github, if not help creating the wiki page. Few people will check external websites. Only Bing and DuckDuckGo shows your issue, not Google. Now it's basically unknown, causing these questions.

This rectangle is for the lot. It can be seen from old maps. You should create a separate object.

2. For back offices and online shopping, please don't use `shop=`

You don't occupy the entire building. Please create a point inside.

Also conceptually it's a shared straight or right turn lane. This may reflect it better.

It could be possible to make the westbound right turn and eastbound right turn share the section at the X-shape, but I want to minimize `oneway=alternating`

3. It's quite ambigious to join 2 roads at a crosswalk. This should be avoided. The other reason for connecting the westbound right turn is it travels through the eastbound straight and left. The eastbound right turn makes a standard turn at the intersection. This should be modeled as a simple "T" shape, not drawing fake turning paths.

On the contrary, the westbound left and straight or right turns are separated. I don't know know what you are doing.

2. Please don't draw a separate line when there is no raised physical separation. The eastbound left turn isn't separated by an island.