Colorful Tabs has come back, it did 48Hrs ago for a while and then stopped working and disapeared, but I get the same problems ie the tab colours all of the bookmark/toolbar area and overwrites the theme, I mean it's brilliant that your'e still trying to get this great addon to work on the nonsense that is Firefox quantum, just concentrate on the Chrome version your sanity will thank you for it.
I do like the way you can use the star icon to drop down the tab window selector that's an awesome feature.