Yeah, sadly I need to support people who find the Autofalcon quite weak. They can't stop even modest efforts of enemies reaching them, and as cool as Pyrehulks look as crew, they are not worth their wages, dropping their equipment way too fast instead of being a deterrent to hostile de-crewing attempts, especially as you have to position them to fire through frontline gaps most of the time, making them easier to reach. Same goes for the Vinderbane. The low range gives them way to limited time to deal damage, and the barrages they can get out before Cav crashes into them in that timespan is just not enough to make up for the range and the positioning disadvantage that they find themselves in quite often due to being low-arc, direct fire gunpowder guns.
And despite what the stats seem to imply there just is... not that much oomph behind it? Maybe there was fear of the artillery in general performing on the levels of amazing that Malakais grape shot cannons can unleash, but that is exactly the kind of performance such units need, having to work against the AI's unit spam and flanker swarms, especially if there is such a focus on heavy guns.
Mortar Muskets worked REALLY better with the high arcs, they are putting more strain on the very limited 'gap shooter' real estate, when they really should be able to lob fun fume from the center or back of your formation, onto units approaching your gunline or already engaged targets, which they are really struggling to pull off right now.
If we get more gear in the future, warmachines/vehicles (hopefully a large, single entity Pyrehulk variant), there might be an even larger strain on the amount of units available for holding-the-line duty, so I hope the fieldgun-type artillery get the juice it needs put in some work in that department.