Can do, What I have done is spent the past 24-40 hours, adding in all 2022 league and club histories for J1-JFL then 2022 League and Club histories to Regional 1 and 2 and added in whole histories for new teams (including those for 2023).
the next thing I did was adjust Attendances for J1-2-3 as they seem like they were last updated before 2019 to include current attendences (+-15-30%) to account for the upcoming post covid era. Then I have added in 2022 ticket prices and sponserships and adjusted reputations.
I am now adding in Prefectural 1 teams that are not present in the database and then any U18/High school teams in the first 3 levels (Takamado Premier,Prince and Prefectural Teams). Then I can actually copy over the structure and make needed changes to systems.
To answer your question, Regional 1 and 2 competitions are already under 1 league then split into their respective competitions to allow them to win their respective leagues.
For Prefectural, This is pretty much impossible since the editor allows up to 26 groups and there are 47 Prefectures in Japan meaning realiostically I cant have it in one league. and ESPECIALLY since each regional prefectural tournament is very different it is much easier splitting it into the 9 regions. from a scouting perscpective if you are in the prefectural leagues it makes much more sense if you were stuck only scouting your and those leagues around you instead of the whole nation at that level.
For cup competitions I can do a better job at picking what level each competition is playable at.