I think it can generally be agreed that both Katyusha and Stuka are overperforming, albeit in different ways.
On Katyusha, I think its primarily a problem with the AoE being too wide, between the AoE and how many missiles are fired, it more or less completely saturates the template area, with very few gaps inbetween. Doesn seem to have that "random" hit kind of feel anymore that I think was good and characterful for the unit.
The secondary specific problem of the dmg on OKW trucks. Overall, considering the shorter cooldown on Katyusha, I find it difficult to reconcile it doing a full 160dmg.
Katyusha could perhaps use a small Cooldown increase, especially inlight of teamgames where many of them can basically be cycled for a continous salvo. But not to the same CD as Stuka.
I recommend an AoE reduction, and, if possible, preferably, a negative modifier vs whatever "type" OKW trucks are, and a nerf in dmg, to say 120dmg.
As to Stuka, I would recommend a slower creep on the missile impacts, for two reasons.
1) There isnt enough reaction time on a frontline traversed by it. Increasing the time between impacts slightly would allow atleast the tail end of the template to react a bit, once you can see what direction it is traversing in.
2) The rate of impacts is ideal for retreat wipes, if you can time the launch correctly. Placed ideally along a retreat path, each missile will hit the hapless unit right on the head at the same pace as it retreats at. There was a similar issue in DoW2 with LGs Creeping Barrage offmap. Its somewhat marginal, because of the timing required, but as VonIvan for example has demonstrated, it is possible and devastating. CoH2 overall tends to frown on retreat wiping, and I think Stuka should be changed to reflect that.
As to Panzerwerfer, I honestly havent seen em used enough, due to the T4 cost issues. Sort of telling of something though, that Katyusha and Stuka both have had enormous threads on them, but Panzerwerfer remains largely a non-issue
I understand that this thread has more or less degraded into a stuka vs katyusha debate, and though I don't think it should be the focus, I realize why that's what the topic is. So with that disclaimer in place.
If we look at these two units separately, which I believe is necessary as they are two different factions functioning against two different enemies, I think we can get to real discussion.
The reason so many people are baffled by the katyusha's effectiveness is honestly, how devastating it can be to the German armies, but more specifically OKW. I'll focus on OKW and RU as that seems appropriate lately. With economic strains, veterency emphasis, and elite unit preservation in mind, the katyusha is simply far too punishing. I haven't played a game since the update where either myself, an opponent, or an ally has not preemtively retreated at the sound of katyusha fire and STILL lost a full squad (often vetted) outright within the first wave. There's still three more. This also isn't considering the issue that OKW is built on a foundation of building decisions. Currently, the katyusha makes that decision for you. In two waves of barrages, whatever truck you deployed is gone.
Now, a lot of people have argued that "well, that's your fault for being aggressive, pay the price." That MIGHT be valid if that was the only realistic way of uprooting these bases. But we all know it's not. Furthermore, this is not just a unit that destroys bases, it goes from blob control on an extreme level to killing off a single squad attempting to capture a point.
The stuka is a separate topic.
The stuka is useful for blob control, and while yes, there is a strong chance a few units may be wiped depending on the group's size, unless the units are marching in a very careful and narrow line on a very predictable path, you're not going to have the same effect as if a katyusha was firing on that same collective. THAT right there, is not a problem -- the problem is how horribly strong it is currently. Let me repeat that. I do think that if you had two of the exact same groups moving in the exact same manner and hit directly by both a katyusha and a stuka, the katyusha should be awarded the higher death toll. I don't like homogenization. I like when differentiating units have differentiating strengths and weaknesses.
The stuka, I feel, shines in very certain scenarios. Clearing out buildings and hitting a set up line. However, when a line, perfectly centered, is squared up perfectly and fired on, you rarely squad wipe healthy and repaired set up squads. Infact, I'd say a third of the time the artillery skips a beat and all but takes a few models. That's not a problem either.
Just to get this out prior to counter points because I can feel this one creeping up fast; to compare mobile blobs and the effectiveness of each is almost silly. The targeting reticles themselves should be enough evidence of that. It's like comparing the effected area of a streamlined laser and a shotgun.
All that said. This shouldn't be a debate where the validity of the subject is justified by another unit.