going through this very helpful list of firefox add-on webextension porting statuses, which also lists already-existing WE alternatives
https://docs.google.com/spreadsheets/d/1TFcEXMcKrwoIAECIVyBU0GPoSmRqZ7A0VBvqeKYVSww/edit#gid=0
many key add-ons are not on the official FF add-on site yet, so this doc is much better than trying to browse that site
@LottieVixen subreddit /r/firefox is a great way to find such things :)
@alyx Nothing about rikaichan on there... Would be nice to know what's going to happen with that in the future.
@mauve the dev's email is on their donate page. ask 'em
@alyx oh my god thank you! <3