I don't know how much credibility they have, but some of the circuits there have been already confirmed, some appeared indirectly in the GT5P weather screen, one (Valencia) was already in GTPSP.
I've updated my list containing unconfirmed tracks (not a wishlist!).
In
light gray are circuits "unconfirmed" by racesimcentral,
In
gray are circuits indirectly appeared in the GT5P weather screen (exception: Special Stage R11),
In
dark red are circuits appeared in GTPSP,
In
green are circuits from GT4,
In
blue are confirmed circuits or circuits seen in screenshots.
There would be in total
61 different circuits/tracks (so around 60 as they mention),
84 variations not counting reverse versions of fictional circuits.
The total number of locations (countries) would be
18.