Let’s come up with new “war machines.”

Guys, you just don't understand the point. Besides tents, ballistae, and wagons, we need to come up with a unique combat machine for each race. For example, a dome that gives a 30% magic resistance to a selected mage unit. Or a siege wall that protects its units from Haven archers. Or some special dendroids for Sylvana. Or a seismic machine for demons...

It could be something like a tent, but instead of restoring health, it restores mana for units (it would be very useful for mages).

Currently, there is an optimal number of combat machines in Heroes, and it would be great if each faction had its own unique design for combat machines. :)

As suggested here, it would be better not to reinvent the wheel, but to slightly improve the old one. Therefore, make alt-upgrades for the machines of each race, and naturally, their appearance will now be different for each race:
1) elves. Add a wasp swarm spell to the tent (it will look like a hive, you can heal your own, or you can cast the spell on the enemy). Add a 15% chance to blind the target to the ballista. It is better not to give the wagon an alt upgrade at all.
2) humans. The tent gains the ability to inspire. The ballista's damage is increased by the "retribution" skill.
3) demon. The tent can summon imps (the number depends on the skill in siege machines). The ballista adds the damage of the fireball spell.
4) mages. The tent summons elementals. The ballista fires a magical arrow through, like mages.
5) necropolis. The tent revives undead. The ballista casts a plague spell.
6) warlock. The tent casts antimagic on one of the units for three turns (once per battle). The ballista adds elemental damage to the damage.
Think of something for the dwarves...

Each race needs at least different skills in the machines. And if they also looked different. For example, for the ballista: for the orcs, the ballista should consist of bones and skulls. For the dwarves, it should be decorated with runes from their alloy, for Inferno, it should be burning, maybe made in the form of a mouth with burning eyes.

I disagree with the weakness of the machines, in the case of the tent, this seriously depends on the timing of the game, if you play like some people for several months, the tent really becomes obsolete, which is perfectly normal (each skill has its time). But if necessary, you can increase the number of shots of the tent or even the initiative.

In the case of the ballista, the question is whether it will be possible to upgrade ranged weapons, i.e., without them, the multistrike branch remains weak. The solution is simple - if you move ranged weapons to the machinery branch.

In the case of the catapult, we have 2 situational, not very useful perks, which would be nice to strengthen. This is what is planned to be done in the Wargame Edition mod (see the first posts of the topic - description of skills and perks). In short, artillery (catapult) will kill part of the troops even before the battle (not only siege), and these enemy losses will be so great that they will pay for not only the perks, but also often the base taken for them.

for each race it is possible to - upgrade machines - thereby strengthening them and giving them - special abilities -
- additional shot
- initiative reduction
etc.