I think "howitzer" in Freeciv is modern self-propelled howitzer because they have 2 movement points.
(and I think their graphic in amplio2 is not appropriate.)
But they are not anti-tank arms.
They fire into Non-Armoured fighting vehicles,buildings,materials,and infantry.
If anything, the howitzer should probably not have the 2 defense or not have the 30 health
You mean howitzer is too strong?
I think so too.
Howitzer should not occupy a city by itself.
It's impossible that modern artillery occupy a city without escort of infantry and tanks.
Also, biplane, jet fighter, and jet bomber are missing from the Air units as well.(Biplane skipped straight to WWII fighter, and then jet fighter and jet bomber skipped straight to stealth fighter and stealth bomber)
But fighter,bomber,howitzer etc, namely modern units,
they are strong and worth researching and producing.
The problem is that only armour is weak and useless units.
Armour should be strengthened or new next-generation units "MBT" should be incorporated.
The graphic of armour in amplio2 is IS-2,I think.
That is anti-Tiger heavy tank and has 122mm gun.
I have disappointed that their actual strength and appearance is too different in Freeciv.