The La-7 is currently a BR5 fighter for the Soviet Union, and there, it is not as good a choice compared to other planes. The direct competitors are the I-185 M82 and the Su-9. While the La-7 has good flight performance in comparison to these other 2 planes (turn time and climbing speed most notably, although much slower than the Su-9 and worse climb), it simply has a much worse armament than the other 2. While the La-7 has two 20mm cannons with 340 rounds total and two 100kg bombs, the I-185 has an extra 20mm cannon with 561 rounds total and two much larger 250kg bombs. The Su-9 has two 23mm cannons with 200 rounds and a 37mm with 40 rounds, in addition to a 500 kg bomb. These both clearly heavily outpreform the La-7 both in terms of guns and payload. I think the La-7 would be fine on BR4 as it has a smaller payload in exchange for it’s superb performance, and since Soviet aviation currently lacks a BR4 plane (which will change when the IL-8 arrives), this could be a decent option to fill the gap.
Of the IL-8 turns out to be a flying brick like the IL-2M then it’ll be more of a side-grade to the IL-10, it still all the more reason to drop the IL-10 down to BR4
German and Soviet planes need a serious overhaul for BR3 to BR5. A lot of them are underarmed or the TT simply lack a proper dedicated fighters and universal fighers. Moving La-7 to BR4 is a patch to get it somehow done but the best case scenario is just balancing overhaul to see where would the La-7 place the best