I wouldn't say the Empire is weak (compared to Wood Elves or Mousillon f.e.) but I see problems on the longer run with vampires. In my campaigns I don't recognise the allegedly necessary 3:1 supremacy for vampires for winning. They usually win 2:1 early game (like yesterday in a siege of Nuln) and even win battles with lower numbers than Empire in later game stages, possibly because every Empire lord sooner or later runs around mainly with recruits. That's in autoresolve where magic does not play a role.

In player battles, at least in the chaotic assisted battles, where the vampires can use magic, it's even worse. A few days ago we barely won a battle with 720 against M.v. Carstein with 660, and the three Empire parties I assisted with my 177 very high tier mercenary party had not the worst unit composition. It was interesting that magic (I have 7 magic caster companions in my party) was of relatively minor value against the vampire army at that instance because it split up extremely, with wide spaces between the units, running around all over the battlefield. Artillery was even less effective.

To make a long story short, are mighty mobile artillery units aka steam tanks planned or even possible for the Empire? If other factions get big monsters, I see a demand for such an unit for the Empire. If it could be coded which it might not.

(Disclaimer: I see this very objectively, and the fact that steam tanks are my favorite WH unit does not play any role. Or does it ...? ).