For a splash, I'm thinking something like the Naval Buildings you made arranged showing the progression, like:
Except with the icons overlapping a little between each one, with the Naval Yard icon at the end and 'on top' as it were in the overlap area. And however much 'blendery' coloring-in is not too much trouble. This to give the notion of the progression of the buildings as you advance and become more modern within the game.
Then just text similar to what you have on both sides of this image:
On the side with the mod 'name' I would just want 'Era Buildings', and then on the right like you did noting Sid Meier's Civ5 Brave New world blah de blah. 'Era Buildings' would be essentially placed where in your image you have the words "Mod Project" and in about the same size. As would the text on the lower-right: same text and size signifiying Sid Meieir's Civ5 etc.
Let me know if that's too, uh, greedy on my part, and we can simplify down from there.
PS: I've been going back and forth with myself on the naval icon 'progressions', and I think this will be the final progression I will end up using.
I really like the icon with the two age-of-sail vessels in port, and so will probably make that the default icon for the Renaissance Era, and only re-assign stuff if a player is also using the enlightenment era mod. Hence the arrangement of the icons in the spoiler.