I don't know yet how RM16 works, but the easiest solution for F14/16 would be naming the folders like sceneassets11-12 ui11-12 and renaming/copying them with overwriting at the end of 10-11.
Here are some concerns I've had for this megamod:
1. Number/font colors.
Let's say 10-11 Arsenal away kit is white, so the numbers and fonts assigned in the DB will be black, and when we go to season 11-12 if the away kit is blue, then the black numbers and fonts assigned in the DB will clash, so the only way to have them white is a new team_xxx.lua file but this needs to be done potentially for every team and every season (or not cared about).
2. Boots.
At some point in time EA changed bootIDs.
So we can't just overwrite F11 boots with e.g. F15 boots because it's very probable that Ronaldo will start wearing Umbro instead of Nike and Messi will wear Mizuno (this one I do care a lot about, but can do it).
3. Teams that were not part of F11 DB but will become important later (RB Lepizig, Sochi, Krasnodar, Morocco, Ghana, Iceland, etc. whatever leagues/teams were not in F11). Maybe they don't get included, maybe just the national teams, maybe try recreating what we can but idk what we can do with clubs that were created after 2011.
4. Young players and modern stars like Haaland, Mbappe, Bellingham - I am not sure, maybe
@RHZhang can advice, can we create them with ages like 10 for 2010? Or Do they need to be at least ~16 in 2010 to be recognized by the game?
5. Promotions and relegations.
That's more of a wish, and I am not sure how this can be realistically done, but e.g. F11 DB Russian League doesn't have its 2nd tier, so teams like Amkar and Saturn will always play there every season without relegation. Probably would be awesome to add a 2nd tier with the likes of Arsenal Tula, Ufa, Ural but IDK what to do there with kits and squads.
In general, It might be important to have a solid starting DB without major missing teams or players.