The flags turned out great! I think it looks better on the top row of maps, where there's some space between them and the map. If you could add that space above the bottom row as well, it would make it feel more coherent
I like the simple title, no cartouche or effects or anything, very nice for this style! The font, while appropriate for the time period, doesn't fit with the other fonts though, imo. But I'm not sure what to suggest instead… Maybe something like Academy Engraved Let? It's a quite lovely art deco-ish font that could tie together with the nation font you're using, but also feel a little more fancy, suitable for titles.