Puntuado con 5 de 5 estrellas

Very very good!! Well done! Everything is working!

Esta valoración es de una versión anterior del complemento (12.0). 

Puntuado con 1 de 5 estrellas

очень, очень плохо, что разработчик отказался обновлять и забросил дополнение

Esta valoración es de una versión anterior del complemento (11.1). 

English Translation: Very, very bad that the developer refused to update and abandoned the add-on.

Account Colors 12.0 works with Thunderbird 68.0. Please see replies to Jaak Hillen and marcus80-PL below.

The reason for the original decision not to update Account Colors to work with Thunderbird 68 was because of the large amount of work required and the unclear future for Thunderbird extensions.