I have just run a few turns to ready myself for the pbem and here are a few things I have spotted.
The West Indies fleet commanded by Wemyss cannot be put into the intercept fleets mode. Even if you take the two units away from him they can't use this order, it says something about no combat squadrons.
Is it WAD that the BEF are listed as reservist elements? It looks wrong, they were far from reservists........
Ammo production looks like it starts at a later date. The fleets only have a limited stockpile of ammo though, could be problematic later. A fleet is using 40-60% of it's ammo in a single engagement.
The British also have a few medium artillery units, in Aden, Australia and Mombassa, but no ammo for them to fire.
All of the structures inside the cities have no numbers to say how much they produce.
The British navy starts out with a lot of units missing elements but no way to fill them. There are no ships represented on the F2 page of the ledger. Is this WAD? When you lose them they are gone, you have to build more from scratch? Or can you buy replacements at a later date?
The marine corps unit starts out understrength with one element of marines. It then receives replacement but these are all "Infantry regiment" types. (Shouldn't these elements be used for the BEF?)
The tooltip for the ability that aircraft have, the "Artillerist" ability, gives a bonus to med and heavy artillery of the stack. It says this in the first part of the tooltip. It then says that the ability applies to all elements of the unit that the element is in. This means that it doesn't work for the whole stack though, it just works for the unit.
I am looking forward to giving this mod a play though Ben, it looks like you have put a lot of work and thought into it.