56リリースの時にブログに記載されていた下記アドオンの動作予定って着手してるのかな。

https://blog.waterfoxproject.org/waterfox-56.0-release-download

Help! Some of my add-ons don't work.
Don't worry. Compatibility with older add-ons is being brought back in the next few releases. A few listed add-ons that won't currently work:
LiveClick
Color That Site
Add Bookmark Here 2
Pure URL
Mozilla Archive Format