You should not use an old and out of date version of Firefox. What is the issues you are experiencing in 60?

Thanks.

As stated in the question, the user experience is seriously broken. I seem to have many issues. Mostly related to tabs. I cannot use a browser without Tab Mix Plus. Other legacy extensions are broken. I really, really dislike that big stupid back arrow circle. I don't want to use Chromium, Opera, Vivaldi, etc. I just want Firefox 52 and my extensions. Why is that so difficult?

You can replace alot of tab mix plus with userChrome.css tweaks, as well as other things you don't really like.

Firefox 52 is no longer safe to use, and the extensions that ran on it are considered legacy and have been marked that for at least a year.