I did. Under the structure it has the correct amount of teams.
One league is the Finnish Liiga, trying to get it to 16 teams, 2 of which are not in Finland, so i don’t know if that matters. But the game says it sees 16 teams and is expecting 15.
The other is KHL, where I am trying to take it to 40, and all the divisions show 10 teams in the editor, but the game says it sees 41 and expects 23, so I’m also trying to figure out why it says 41 when I only see 40.
I’ve managed to mess with other playable leagues by replacing them with the same number, so I think I have that part down
There are multiple places where you must change the number of teams in the Rules & Structures screen. The error you're getting is because you haven't updated one of those settings or you haven't assigned enough teams. Off the top of my head, the following settings would need to be updated:
Basic Data tab -> Number of Teams
Structure tab: If you are using one of the "From Basic Rules" team picking rules (see the Stages tab -> Rules sub-tab for each initial stage) then you must assign all of the teams here. If you're using the "From Database by Base Comp" setting then you need to set the League and Detailed Division for each team via the Clubs screen.
Stages tab -> Number of Teams (for each stage tab where the number of teams has changed for that stage)
If you have also changed the number of games played then you may also need to change:
Comp Rules tab -> Max league games
Stages tab -> Stage max league games, number of dates and rounds (for each stage tab where the number of games played has changed for that stage)
Assuming that you're using the latest version of the Editor (v1.0.2 and I'd highly recommend running the latest version) then there is a Status tab which displays a limited range of warnings which might help.
Let me know once you have found the issue and I may be able to add a warning message on the Status tab for future versions.