I would prefer Steves list (fixed to remove all the 0-x business, free SC and the other niggles) to that. Thunderhawks and stuff are loyalist and recent rebels, not traitor legions.
While watching toast with surround sound what would be your thought on a proper grand company? Okay 20 stands is out

What about a guard 12 + Lord style? It could then infer the loyalists adopted their superior organisations for their own armies

Arty wise I like 3 artillery types in the list - the basilisk and then equivalents for manticores and bombards (both of which were used in the heresy but would have been impossible to maintain logistically).
I would also suggest different weapon configs for the Titans. Make them siege breakers?
So say inferno weapon on a warhound equivalent (well the feral practically is this), an assault rather than stand off warlord (tearing down terras walls) and perhaps a multirole reaver equivalent to the loyalist MRL/TLD/PF. With tails, chomping mouth etc etc

Maybe for a rebel reaver inferno weaponry, rockets, CC tail and head, gatling style weapon.
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