Yeah, that's basically just a stupid decision on their part, but I don't have any involvement in that project, so I don't want to try and change that, but just stick to the rules of your language. If your language doesn't normally do that (few languages do in my experience), don't use Those Annoying Capitals, it will just look silly (and possibly even unprofessional). If I see something written like that in Norwegian, I automatically think that it's autotranslated garbage, or that the person who wrote it barely even passed primary school, since they obviously don't know how to write Norwegian properly.
I agree, but as it's not a rule of english language, it's either a mistake of iNaturalist developers, or a particular will independantly of grammatical rules. So if we think it has no sense, the english messages must first be modified, and then the translations will follow. Otherwise, why this change in english only?