Idea: Provide Mobile Arties (mainly the Trebuchet) with the ability to fire while moving
Reasoning:
TL:DR - Sniper+Shield mix is incredibly oppressive and while UEF has some interaction possibility due to Spearhead/Demolisher/Parashield mix, Cybran is left out in the dust hard.
I'm going to be looking at this from the perspective of 2v2/3v3 play, I don't really see this problem existing quite as largely in 1v1 or larger teamgames.
So with the recent balance changes to the T3 stage we've seen the introduction of a general intended meta with how t3 units counter one another.
We have Titans/Loyalists as the raid heavy T3 units intended to manage the transition from t2 to t3 and potentially deal with loose mexes around the map.
We have Harbs/Othuums that bridge between Titans/Loyalists and Percy/Bricks and are able to handle the former quite well while losing to the latter handily once mass equivalent numbers are on the field.
Then we have Snipers as the sort of penultimate answer to the "direct fire arms race" where you sacrifice everything in order to get range + massive alpha. They are the Seraphim/Aeon answer to Percy/Brick mixes.
However, this then gets into the intended counter for the sniper + shield mix of Aeon/Seraphim. The intent, as far as I'm aware, was to make snipers possibly countered by Titan/Loyalist spam which the snipers would have a difficult time retreating from while also not being quite as mass concentrated as the siege bots.
However, once you build up some sort of significant concentration of snipers alongside shields and some assortment of harbs/othuums to handle things that manage to get close, this counter becomes unrealistic. If the initial switch to titans to counter the snipers fails, you're going to have a tough time managing to rescale enough titans to attempt a push once again and the enemy will likely have begun including more othuum/harbs into their mix while also being able to secure the reclaim of your initial failed titan push. Or at the least, be able to deny you it while continuing to get good trades with their snipers.
The next typical solution is to utilize t3 mobile arty as the indirect fire method that attempts to beat snipers at their own game while sacrificing even more utility in defeating unit pushes. The big problem however, is that t3 mobile arty is unable to fire while moving meaning that snipers will still force you to concede massive territory until you get to some particularly safe location where you have your own stationary shields, pd, whatever. This is even MORE difficult against aeon which can make disruptors to efficiently defeat your shields and then snipe your mobile arty if they have no t2 arty support.
The UEF have a bit more leeway here because they have two units that are reasonable responses to sniper + shield spam. If all else fails, they can always make a fatboy which is supreme at forcing snipers to concede land for obvious reasons. But it seems quite obnoxious to have to be forced to transition to T4 tech to respond to this inevitable unit mix, particularly in 2v2s on maps like Funeral Plains or Canis where you have some open space in middle to abuse.
The UEF also get the spearhead, which is basically the solution I'm trying to give Cybran to answer Snipers. Spearhead can shoot while moving while also having double the damage for mass of arty. UEF also has their own mobile shields and so does not need to worry about their spearheads being sniped by t1 bombers provided they have proper coverage. The spearheads are capable of taking shields down quickly while then allowing the occasional demolisher to land a shot that can kill the low hp mobile shields and destroy the protection of the snipers.
It would of course be easier to use this unit mix if demolishers could also move while firing, but UEF has some ability to answer the typical sniper+shield unit mix. Cybran on the otherhand, is just boned. Not only does their t3 arty require them to be stationary, but they also have no mobile shield so they can't really keep forcing snipers back without immediately losing their arty to t1 bombers. They specifically really need some adjustment that allows them to handle this mix without being forced to go into Mega and T2 arty base. The best solution I can come up with is allowing trebuchet to move while firing, which also has some synergy with their mobile stealth as it makes it more cancer for snipers to actually target the arty as they retreat/advance.
Replays:
https://replay.faforever.com/10902518 - Game of me having to deal with Turbo's sniper mix, granted this was when I was still adjusting to the T3 changes and didn't have the idea of using spearheads/arty to handle them. Mainly including this to showcase that snipers really do lock you down to some sort of indirect fire response.
https://replay.faforever.com/13326893 - Just a typical late game sniper mix game in a 2v2.
https://replay.faforever.com/13309613 - This was basically the game that made me realize spearhead is a necessity for UEF if you plan on handling sniper mix.
https://replay.faforever.com/13360108 - A LotS game of Bully using spearhead against Blackheart sniper mix. Seems to do decently well, but again, Cybran has no similar response.
Problems:
It's very easy to revert back to the old situation at the start of the T3 rebalance patch where T3 arty was extremely oppressive and capable of crushing armies themselves. While this is a possibility and a reasonable worry, I do feel like it won't be as significant of a problem if you only give it to Cybran t3 arty and work from there. Cybran does not have shields (and their stationary ones are garbage anyway) meaning that air is a decent counter for their indirect fire relative to other factions. I also feel like Titan/Loya are a much better response to indirect fire than they are for snipers and that harbs/othuums can also supplement in that role as needed.
Other Ideas:
The only real things I could think of to address this problem (particularly for Cybran) were more invasive than this change. Things like giving an absolver ability to other units and things of that regard. I figured this was the least invasive change that would have as few reverberations across the rest of the meta.