In English it is fine to describe somebody as an ambassador of something, like you say, but it is always an informal description of the person, not an officially stated title. So a newspaper might describe a businessman as "an ambassador from such and such coalition" or whatever, but the man himself would never introduce himself "I am ambassador Jones", that would just sound pretentious. But the main point is that even though people may be described as ambassadors, nobody ever refers to their office as an "embassy". I am sure there is a different English word you could use. "Bitcoin Outreach Center", or something like that.