Actually, Zvezda's idler is also in a wrong position (sort of), you can see where the axle was broken and almost made me throw the kit into the bin. Fortunately, good non-expensive workable tracks appeared (AFV Club). The idler on Tamiya's T-34s is too close to the first road wheel and too low, you can't do to much to fix it due to the metal rod (height can't be fixed). You can position the idler on Zvezda kit, but if you place it in the right position, the tracks will result too short, if you want a good fit of the tracks you'll have to place the idler the closest to the first road wheel as possible, and it will look like a Tamiya kit, but not that much. As I was using AFV Club tracks, I also decided to modify the idler wheel mount, even if it will not be seen (that's just me):
Same modification with some scratchbuilding can be done on Tamiya kit, but AFV Club tracks (or other workable tracks) must be used. Best regards.
José.
P.S. The pics are form 2 years ago, but the project is on hold. I added some more bits, but I'm a bit lazy to replace all handles and bolt heads (I have hex rod though).