Vinding

Football Manager does not have "Serie 1 Fyn" added. You must be using some sort of user-made database, probably from the Steam workshop  

They have "added" cities etc, which are not in the game, but are available for activation through the pre-game editor. So when you activate lower leagues in Denmark - you get Serie 1 Fyn - and this is where Vinding has been added, and not Vindinge. Here is the database for you see. From what I understand from the creator of this, basically just activated what was already in the database, and didn't change rules, clubs etc. 

Denmark-Lower-League-Tier-8 (1).fmf

You must have misunderstood the creator then.
No leagues below Københavnsserien, Sjællandsserien, Fynsserien or Jyllandsserien is in FM by default.

Vinding Sportsforening is in FM by default, yes. But it´s in the "Danish Lower Division"-league, which is just an arbitrary league for teams which is below the level of leagues add in FM by default.

Whatever FM users decide to do with that data, I have no control over  

The guy who posted the database, said that he did not make any changes to the database, because it would have taken him too long to get it all right. So he says he just "activated" the leagues etc. which SI already created. I just quote what he says. 

Well anyways for future reference, which clubs are in which divisions you can use "https://dbu.dk/" even for lower than Fynsserie if needed.

 

If someone is just activating something in the database but not in turn making it work then unfortunately its likely things will go wrong. Keep in mind the FM database is inclusive of a lot of data including football teams and even countries that no longer exist. Anyone could "reactivate" any of these by using the pre-game editor but they would either not work, or have a lot of problems.