Reading through the ETO rules - and I am quite concerned about the workaround of 'Card Selection'.
Personally I do not believe it works well in a combined ETO game, that the Axis falls shorthanded in cards as well - especially as they'd still be bound by 1 Large card per season vs 2 of their opponents, and they'd be even more starved if for reasons their enemies pick up on Small cards (which can still be excellent).
Probably to have matching selections per Theather or so, or 'Game' would pan out better, or is just easier to balance and fine-tune. (Card Selection for Eastfront, Card Selection for Mediterranean / Italian front, and Card Selection of the West Front - or at best to bundle the later two together.).
Just expressing a concern - as it seems quite a feature of the game to select cards, and if cards are then bound by 'reacting' to larger events of the other part ... it seems quite unfair.
Axis may have a single stack of cards to pick from, if that helps, to avoid double production bonuses or the like (If they can afford these cards).
But otherwise Italian Large or Medium events may be really short handed as well, especially after Barbarossa hits.