The Pak-43 absolutely needs that shoot-through-buildings thing, otherwise it would become trivial to just bumrush it with tanks, or snipe its crew or,... you get the idea.
I know that some factions have uneven access to artillery than others, but, hey, at least the Pak43 is doctrinal.
The solution for Pak43 (also applies to Elefant and JT) is to just train your ears.
The unit makes a very distinct sound when it fires, which should give you a clue that the area is now a no-tank zone, until you can come up with your response. 500MP just doesn't just grow in the trees, you know!
Non-doctrinal counters
(apart from infantry bum-rushes)
Soviets: Katyusha, satchel charges
USF: Major artillery
UKF: Anvil Artillery, Firefly Tulips (if you fire Tulips at a decrewed team-weapon it becomes insta-gibbed; sort of like T-34 ram)
British 17 Pounder:
Pros:
- Invincible crew; cannot be taken by the enemy
- About 3-4 times the HP of the PaK43
- Doesn't need a specific commander
- Can Brace
- Has more range than the PaK43
- Can be covered by a mortar pit
Cons:
- Costs 70 fuel
PaK43
Pros:
- Can shoot through buildings
- Doesn't cost Fuel
Cons:
- Countered by any artillery immideatly
- Costs 600MP
- Very little HP
- Only available in some commanders
- No brace or anything
TBH I would take a 17pounder over a PaK43 anytime.
You are ignoring one crucial aspect of the 17-pounder:
- It has a gignormous hitbox, and a small HP pool (900), which makes it trivial for tanks to counter the 17 pounder (not to mention anti-tank guns...)
A stationary AT gun that can't defend itself against tank rushes is just plain useless.
(also, both Pak43 and 17 pounder have the exact same range)
Solution: make the 17 pounder a clone of pak43, and do something with target tables so that it doesn't auto-die to Walking stuka barrages (due to the fact it is super accurate).
(off-map artillery instagibbing pak43/17-pounder is valid, since everyone already does this).