Thanks to PabloV, Mirage Feathers now supports Spanish.
To change the language, you can go to Options Menu → Page 2 → the last item.
1.005 Spanish Language Support
Source: Steam Community (opens in a new tab)
Build and release context
Steam update times within 24 hours of this post. Matching dates do not confirm which build it describes.
Build 18081606 · public branch
Steam updated · First observed