gbf-raidfinder uses Twitter's streaming API to find raid tweets. However, boss names aren't hardcoded into the program -- instead, they're automatically discovered when users tweet about them.
The gbf-raidfinder backend uses the search terms 参加者募集！ and
I need backup! and parses the tweets to get the boss name, raid ID,
and other tweet information (boss image, user details, additional text).
Tweets that don't parse or aren't tweeted from the official in-game
Granblue twitter client are discarded. Tweets are then grouped by boss
name. When a new boss name is found, it gets added to the list of known
bosses.
gbf-raidfinder is able to automatically translate raid boss names between English and Japanese by using image similarity.
Each raid tweet contains an image of the raid boss. The English and Japanese versions of the raid boss image are almost exactly the same, except for the boss name in the bottom right corner.
When a new raid boss is found, we take a perceptual hash of the topmost 75% of the image (to ignore the differences in the bottom right of the image). If a boss has the same perceptual hash as another known boss, and they are the same level and opposite languages, then they are determined to be the same boss.
This has worked perfectly with one exception: Lvl 120 Medusa has different Japanese and English images. There is a manual override for this boss.
Not all bosses have images -- new event bosses might not have an associated image until some time after the event has started -- so these bosses remain untranslated until an image is available.