Look around in the forum, there are more discussions about common names, use of an ‘externa provider’ and for example this file https://drive.google.com/file/d/1NP-ApMmLqdyiZFdI4w28e89a3_2WVOxY/view
from this topic https://forum.inaturalist.org/t/which-lexicon-to-use-frisian-or-west-frisian/20679.
You can also check feature requests about common names.
I agree you should use the correct capitalisation when you add common names because iNaturalist cannot handle all languages in a correct way.