The acceleration values posted are literally how much speed a thing gains in 1 second.
They do take a difference amount of time because the Churchill has much faster acceleration and deceleration, what are you going on about. The game engine isn't some complicated physics sim it's literally "the thing with the highest acceleration accelerates to a set speed the fastest"
This isn't even getting into the fact the ST has assault gun pathing with is literal cancer.
I'm going about the value that you so stubbornly defend as important actually being negligible, because it doesn't matter how fast ST or how well/bad it accelerates IF YOU WILL NEVER EVEN SEE IT aiming and shooting at you.
Chburchill needs to get there close and personal, ST don't, you're arguing the mobility of artillery unit that shoots from FoW, where CAN'T SEE IT, it doesn't matter how fast it accelerates, because it doesn't chase anything and after getting hit by its rocket, you won't be chasing it down, but counting losses.
For the same reason pathing is irrelevant, ST does not need to go after a target, exposing itself to its sight.