Modify Players DB

Hello, I would like to edit some of the players in the db - i.e. I'm using SWOS 2020, but Polish National Team is outdated, so I would like make some changes. I've used the editor from github, loaded and saved the files, but the game does not reflect these changes. 
Can you tell me if it's possible and if yes, to which DB location I should point the editor. 
Any hints much appreciated.