Generally speaking the charts were pulled from HTC's own servers. Most of them were fairly up to date, however they aren't always fully reliable...
Not all of them are at representative weights, and not all of them show the differences. So for the Seafire they have absolute identical climb rates to the spit9 because it has that... at an arbitrary weight loadout that can't be achieved in the hangar...
They're good for the most part, but you can't 100% rely on them for everything. That being said, because they're good "for the most part" you can trust the wiki charts, "for the most part" (see how that works?).
Exceptions to this rule include:
P-40E (drastically remodeled)
Seafire (bogus weight skews climb)
Fw190F8 (bogus weight skews climb)
...and possible a couple of others...
P.S. Do you really need a 1.9MB animated GIF in your sig? Just sayin'.... seems excessive.