Alright I'll start by using the statistics from this topic: https://www.coh2.org/topic/81227/second-commander-rework
The Royal Artillery Regiment's Early Warning is a good no-brainer ability that requires no player input however I think that it can be replaced by something that would provide the same effect but more, uh, dynamic and making sense I guess? That would be the Recon Section, which is present in the game files and was even used in the UKF Alpha to come with the Valentine as a small battlegroup of sorts for earlier reconnaissance purposes, altho I agree that that would make the Valentine's job a bit overlapping so it would really be up to the player to decide if he would like to invest some early man power (or munitions) into a Recon Section (as a separate call in unit like the Tank Hunters or as an upgrade, hence my munitions suggestion in brackets). They would be in the same role as the OKW's Panzerfusiliers with their flares, but instead of providing sight for the Jagdtiger they'll be providing sight for British Artillery.
The other thing which I want to touch upon is the Perimeter Overwatch, it's a very underwhelming ability and a munitions sink due to the large amount of enemies that can be present in your sectors at the same time but only the 2 base 25 pounders can fire at a single target at once, so to that end I suggest replacing this ability with SnakeyEye's 25 pounder emplacement from his "All Units Mod" which would also directly buff the "Concentration Barrage" ability, having more 25 pounders able to fire at the target but perhaps it's ammunition cost should be increased with each howitzer to keep things balanced.
Overall I think that with these changes the Commander would still remain all about Artillery and sighting for it and would provide the option to the player of going for an early sighting unit or a mid-game armored such that also costs fuel and arguably take on other such units and going for a mobile artillery or static such but with the ability to join in with the Concentration Barrage, which is a fair trade off in my book.
The Second Commander I'll be talking about is the Tactical Support one but I'll be short as it's not even my suggestion but something I really liked by another person: I recently read about a suggestion of the Recovery Sappers being able to "secure" territory for additional resources and for the Observation Posts to grant their ability to FAs as well so they're not completely useless when not near the fighting which I really liked.
I guess this would serve to give this commander more of a point in terms of support instead of being completely useless, especially for it's last ability.