I actually investigated with the editor, there are a lot of teams like that in the DanFm English lower leagues database for FM23 (its not an actual feature on the original database it seems), the highest one is New Salamis in 8th tier, i've made a spreadsheet of all the ones i could find, ill quote it with my main account
Teams that produce majority foreign newgen players(Update: an actual spreadsheet)
in Football Manager General Discussion
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Here is the Spreadsheet https://docs.google.com/spreadsheets/d/1JnpAh71KbsCdUqBdLu63nSX8oEm6z9VTyJVxyXUGkJE/edit?usp=sharing