The listing is way too confusing and not accurate. For such a great airport and scenery the gate selection is a let down
This has been discussed so many times on the forum.
The parkings have been all set to GA not because of an "oversight". They have been obviously INTENTIONALLY made like that, to get rid of the default ground vehicles, which will both slow down fps and will interfere with objects and ground details from the scenery. This is a common method used by many other developers.
HOWEVER, since GSX is free to use at JFK, so we can safely assume you can use it. And with GSX, you can select a parking from the GSX parking list. The GSX parking list is way better than anything that could be done with the very limited default FSX naming conventions, which IS "confusing".
GSX, instead, properly name terminals with their real world name, and group parkings by name, to make it easier to select them. And it tells you if the parking is free, if it has a jetway, and if it can fit your plane, by checking the proper parameter, which is the actual size, not the "confusing" default convention of Small/Medium/Heavy.
And, the GSX parking selection menu can handle parking names that are impossible to do with the FSX naming convention, for example something like "Terminal 4 Parking 35A" is NOT possible with the FSX menu, but it can be done in the GSX one.
Coupled with the "Just warp me there" option, the GSX parking menu can REPLACE the default "Go To Airport" function so, there's no reason to still using it, especially if you are starting a flight from a gate.
Just place the airplane on the default runway with the FSX "Go To Airport" menu, then use the GSX menu to select the parking using the much better GSX selection, and then select "Just Warp Me There" option, which will JUST place the airplane, without doing anything else with GSX.