Rated 5 out of 5 stars

per Firefox user 22ae43 el nov. 2, 2018 ·

It *does* work for sortiing accounts but you have to manually install the latest pre release ie. 1.2.0pre3 as per one of the other reviews.
https://github.com/Ximi1970/Manually-Sort-Folders/releases/download/v1.2.0pre3/manually_sort_folders-1.2.0pre3.xpi

This review is for a previous version of the add-on (1.1.1).