Some were first discovered in GT Sport, and some were first discovered in GT7.
- Watkins Glen for example, was added to the list during GT7. The discoveries of Albert Park, Circuit Gilles Villeneuve, Red Rock Valley & Zell am See were also from GT7, not GT Sport, but have yet to appear.
- Daytona, Trial Mountain, Deep Forest & High Speed Ring were found in GT Sport, but would debut at the launch of GT7.
- Road Atlanta, Grand Valley & Eiger Nordwand were found in GT Sport, but it took a longer time for them to eventually appear in a GT7 update. Grand Canyon, Akasaka Short, Cape Ring & Mid-Field Raceway were also from GT Sport, but have yet to appear.
- Lake Louise may have existed as a file known as "test_snow_oval" at one point, but not by its proper name.
In short, these combined
datamine lists have contained every new track & layout featured from the start of GT7 to now (Lake Louise debatable). So it's a pretty decent list to base guesses off of.
It should also be noted that
Polyphony will have added new files since the latest datamine that we don't know of (like Motegi perhaps), and it's very possible for something to seemingly jump the queue and be added before the rest of the datamined tracks.
Road Atlanta was in the code for a long time, but Watkins Glen was added to the code
after Road Atlanta, & released
before it. I think it may have only been a few months between the discovery of Watkins Glen & its release, compared to years with Road Atlanta.
This is not to say it only took a few months for Polyphony to
make Watkins Glen of course, just that the
age of files seems to hold no relevance to its release.