Catch-up mechanic on the Legacy Path

When looking at the Exploration Age legacy path, I noted some symbols in the bottom-left that I haven't seen discussed. I wasn't sure what they represented, but I think they could be bonuses to catch-up in the following era if you didn't get to the first reward for a legacy path. The devs talked about splitting the game in 3 eras as a way to keep every in the competition until the end (rubber banding).

What do you think each of them could be ?

Edit : According to the game guide on Ages (https://civilization.2k.com/civ-vii/game-guide/gameplay/ages-explanation/), they are Dark Age Legacy. Like Golden Age Legacies, they could be additional choices of bonus on which to spent your legacy points at the beginning of the next age.

Antiquity Science path : get you extra science in the next age ?

Antiquity Military path : Locked because the first reward was reached (same for Economy & Culture)

Exploration Science path : Eureka for Flight in the Modern Age?

Exploration Military path : Get you an extra commander with a promotion in the Modern Age?

Exploration Economy path : Extra culture and ressource (leaf symbol as in the menus) in the Modern Age ?

Exploration Culture path: You get Robin Hood in the Modern age ???? No joke, it could be a unit, but it doesn't look like it belongs in the Modern age..