Here's my take on the thing.

I don't see the harm of "community post" or "PSAs" (like involving the entire ecosystem i.e. Blocktrades' updates) being translated by those who are willing. But, they'd have to be good though and I think the audience would know.

For project-specific announcement, it might be better for someone to be in agreement with the original author, formal or informal, about translations.

For personal blog posts, I think that's where gray areas and wrongs could occur. The last thing we want is someone who peruses through Hive and just translate other people's personal posts without their permission for upvotes.