Thank you for a reasonable and argumented reply.
I can see how Stuka is more of a problem in team games, but then again, a lot of things are different in team games. I don't really know what to say on the count if it is balanced or fair. I would say I think it performs for cost. If it cannot kill static support crews, what precisely should it do to justify the cost and tier/faction placement?
What else would you have it do? If you reduce its damage or AoE, you are left with a fuel sink noone would ever use in their right mind. Area, non-linear barrage has been suggested and I suppose it could work. But please take a look at the average number of kills a Stuka gets in a game (even team games) and offset it with its costs.
The issue with Walking Stuka is that its first barrage can be absolutely devastating and gamebreaking but after that, it doesn't make much for its price, I'm aware of that. It doesn't seems fair to me for both sides, the allied player who lost full health units in a unavoidable attack and the axis player who paid an expensive price for a slow arty piece that relies only in its surprise factor.
It could receive some lesser changes, like less barrage range, having to get closer to the enemy or a bit of damage decrease meaning that full health units could still have chances to survive a barrage. In exchange it should have a cost decrease or faster cooldown in between barrages.
By the way, I'd gladly pay 150 fuel for a Katyusha with the damage output of the Stuka, as usually I've to make two Katyushas in order to have a combined barrage even less powerful than the stuka's.