Technically, the SU76 is 8.3% more accurate than the Stug at range 50. The difference in accuracy becomes narrower in different ranges.
So it actually more accurate than the Stug as I pointed out (even if number was off).
What is more important thou is the fact that TDs (+60) are too accurate at long ranges especially vs medium tanks that are outranged by x150%.
Tds should have lower accuracy than ATG that can not relocate fast and keep the distance.