Then you've managed to create something that is not only not unbalancing, but works well with your world also! Congratulations, it must be very gratifying.
....see, the point was that's exactly what these regional feats are.
Not really, no. That would be true if you got an effect just for doing something, but these still have to be purchased normally with a feat slot. Not to mention the fact that your choices among them are limited to start with, and you can only take one, more than makes up for the fact that that it's slightly more powerful (and only slightly).
See, as far as I can see, this is bad balance-fu. You have to pay the cost, but you get a greater benefit than someone else who pays the same cost....maybe not significantly....but it's kinda like in normal D&D, 1 first-level feat = 1 first-level feat. In FR, 1 first-level feat = 1 first-level feat +1. It's not game-breaking, but it is unbalancing....a smidge.

You pay no extra cost for that +1.
Limiting the number and choices isn't a balance factor. Even if there is only one of those one-level uberclasses per continent, the class is still overpowered on it's own merits. It's on an extra cost, it's just that your +1 is limited on what it can apply to...it's a limit on the bonus, not a cost to pay for the bonus...
Now that's just plain ridiculous...the Greyhawk boys have regional feats too.
Well, no, not really....not if the PHB is taken to = Greyhawk (which was my assumption)....but basically, whatever world is crafted from the PHB is now 'worse,' just like any character created in that world. The FR character is more powerful. Though my example was ludicrously exaggerated, I'll give you that.
With that outlook, major artifacts must tear you up inside.
Major artifacts are more plot devices than anything else...PC's don't expect to get their hands on them unless there's a reason within the plot, and then don't expect to be able to 'abuse' their powers for very long. However, FR PC's expect to get these "+1 feats," and expect to be able to use it to it's greatest advantage. It shouldn't matter how exotic or rare, say, a mercurial greatsword is...once the PC's get one, they're more powerful than ever before, and if the PC's never get one there's no reason to have them in the game.
Honestly though, I don't think any of the regional feats are more powerful than, say, a feat that offers a permanent, unnamed +4 bonus initiative.
Well, when one comprable feat gives you access to a single martial weapon....vs. FR's 'all martial weapons'.....that's more powerful than any standard feat...frighteningly so...