The kerbs can't be edited in GP4, can they?
Compare them with videos, oboard and otherwise, of F1 circuits. Quite a number of GP4 kerbs, particularly Malaysia and Brazil overall and, say, Belgium at the outside of the BusStop, are too narrow.
Neither can the location of the graphics in GP4 be edited, so that while GP4 track graphics addons can change the adverts at a track, they can't place them in the proper places. Nor can they remove, add, or reposition any objects at all.
I'm also a little surprised that GP3 track graphics modders have hardly ever (you're probably the only exception, with your 2001 graphics pack, that comes to mind) bothered to make new textures for the GP4 track kerbs, seemingly just assuming that the original GP4 kerbs' appearance is beyond reproach, when a look at some close-up photographs will show this not to be the case.
The original GP3 kerbs were almost all a bit too narrow. I do admit that GP3 addon track makers have had a strong tendency to make their tracks' kerbs rather too wide, (which is something which I have complained about in the past).
As far as track configuration goes, track bumps and miniscule camber differences aside, as an example, aren't your GP3-2k Magny-Cours and Melbourne tracks nearly identical to the better modified GP3 versions?
Many racing games in the past have claimed to have gone to extreme lengths to model their tracks correctly. Invoking the near sacred term GPS seems to impress many people mightily and stifles many dissenting views regarding such claims. Just how accurate is the best such data supposed to be? Inches, feet, yards, more? If GPS data is allegedly so incredibly accurate why is it that, to this day, it is still mooted as to just how high the world's highest mountain is, and, indeed, whether it may possibly be K4 rather than Everest? Personally, I'd much rather trust the evidence of my own eyes in comparing game tracks with videos and photographs of real tracks. (As an aside, your GP3-2k Interlagos track strikes me as being a bit too short and also a little too narrow. Is it possible that either you scaled it just a tiny bit incorrectly, or perhaps such is the case with the original GP4 track?)
"I don't understand why you think gp32k is hard to edit, it isn't."
It depends on what you're comparing it to. Compared to GP4, it's a breeze, however, there aren't any nearly, all-in-one, one easy click editors for GP3-2k like GP3Edit or even GP3Master for GP3, are there? Even carsets must be a whole lot more difficult to make for GP3-2k than GP3, else why would there be so far fewer of them, and why, to this day, would even a couple of the very few past F1 seasons' GP3-2k carsets still not have had menu arts made for them?