Do player develop when i send them to non playable league?

my b side is somewhere in non playable in spain, with no matches in fixtures. but when i look at the player history in players in my b team, it says they played matches.

From experience I'd say they do, yes. Despite there appearing to be no scheduled fixtures, I think this is put down simply to the detail level rather than the club playing no games themselves. Players are getting matches, it's just that you can't look into these matches... If that makes sense!

Same with my B team as 1860 Munich's B team play in the Bavarian league, so they still get 'matches' and develop to an extent.