I totally agree with you on terrain. Played a huge role obviously, and just can’t be shown on this map. Weather as well at times, but again, only so much you can do.
You make a fair point on limiting rounds of combat because of how far and fast some fronts moved compared to others. Again, not 100% how to quantify that in a game though. Unless I’m misunderstanding you, you’re talking about a similar idea without limiting the number of rounds of combat to three. But what’s stopping the defender from retreating after one round of battle each time then? I guess I feel it still doesn’t fix the problem of fast moving fronts, but I don’t know.
You’re right, naval combat is another thing all together as well. I’ve thought on that one too, and my initial thought process is that combat shouldn’t necessarily happen every turn. If we assume ships can share a territory in the same manner that land units can finish a turn contesting a territory, we could role a die before each naval combat, a role of 1-4 battle commences, but at a 5-6 nothing happens during combat, as the two navies couldn’t locate each other. Having planes out scouting could add one to your dice role though, to better help search for the enemy fleet.
I haven’t come up with any decent idea about air combat either, but again, I agree, it would be nice to have some sort of aerial combat that would dictate local air superiority in each battle.