Maybe you could change 1 thing: we are only able to work on 1 main role on youth players, but, for exemple, if we have 3 youth players, they will all work on the same main role. My sugestion is that we can change main roles, if i have 3 youth, i would be able to work 1 as supp, another as mid and the 3rd as top. and even with diferente investment on the roles at my will (10K on 2 of them, 30K on the other one, for example)
The devs have already addressed this in the Academy page when you hover your cursor over the title "Investing in youth academy":
"Youth academy is place to gather new players. It is not highly recommended to invest in it in the beginning however later when your older players start to get old you probably will need regrowth. You can currently focus your academy on a single role as this means that using market will become important. You will have the potential to get returns from training on the market when other players are seeking to fulfill their roles and you will have to get your other new players from market by bidding."
Anyway, when wanting to build a full team of youths, most people buy 5 13yo youths from the academy, hire 4 of them immediately and train them with coaches, and leave 1 youth in the academy to train with 100k. That way you can cover all 5 roles.
its a good way to avoid that the top players still can be dethroned. if the best manager could have 5 players on different roles in the academy, and as soon as their current squad get old, their youth academy players are ready and continue to shine all the time.
I like the "only one role" rule, it adds competition, market activity, market productivity, op-disability and other words ending with "ty"