viliml said:
Tell me more about BrokenEagle's automation
BrokenEagle has a specific bot that goes through and retrieves the alt text from Twitter posts, simple as that. Danbooru does not currently automatically retrieve Twitter alt texts, thus a user-made solution. The format you see in Sessyoin Kiara's post is the format that BrokenEagle's bot renders alt text, example, and he has been using that format consistently since late June 2022.
The vast, vast majority of alt text commentaries on Danbooru are thanks to his bot, effectively imposing his chosen formatting on the site even if others disagree with it (see Nameless Contributor). So even if there is a standard, it isn't codified nor is it universally accepted. That then causes trouble if, say, someone wants to correct the broken alt text in Tumblr commentaries, because if there is no universal standard, what are you supposed to correct broken alt text to?