Hi,
i think, there is only meadow and only sometimes seasonal objects related to animal husbandry.
I'm glad you're working with JOSM.
If you like, you can delete these "buildings" yourself using the "reverter" plug-in. In Germany, there are often regional aerial imagery in JOSM that is better than Bing or Esri, for example this:
Brandenburg GeoBasis-DE/LGB dop20c.
Greetings and happy mapping!