Ok. Obviously I'm not going to convince you so we might have to agree to disagree on this one. A nerf seems pretty warranted to me but maybe I completely off on this. I would like to hear some other peoples opinion though or if they have any other suggestions
Jackson has been nerfed indirectly with Panther armor/health switch, you already need one more penetration shot to take down a Panther. Jackson isn't already the go to counter Pz4 since both units able perfectly capable of winning the engagement based on who fire first and misses, nerfing long range pen isn't going to change that situation, same goes vs Stugs, long range pen nerf isn't going to change anything in the matchup.
So I ask you again, what do you want to achieve with that nerf? We already know (after 4/5 years of Coh2) that having pen standing on RNG isn't working and bring more frustration than anything else. Zarok proposal is clearly more interesting here.
Personally I don't see the Jackson overperforming, it doesn't have alfa strike like the FireFly, you always have plenty of time to react and escape and even if it has more hp diving in is still a huge risk, at the same time diving in to take it down is also more risky.
I can't really say in 4vs4, but 1vs1 and 2vs2 you need at least 2 of them (or a mix with your partner TD) to take something down on late game or use combined arms (usually atnade to let you finish off the target).
About vet1 dps boost, let's not forget the armor boost Axis tanks also get at vet1 and blitzkrieg that can be used just after a shot so you can escape during the reload time.
Honestly What have been done to the panther is in my opinion a really good change making panther more reliable and other TDs (not only Jackson) less powerful vs them.