IS there a new add-on to change the way the bookmarks toolbar works?
I would only like to see the icons and not all the titles, without me having to remove all the text in properties.
The old add-on is no longer working.
You might be able to find some potential replacements in our bookmarks collection: https://addons.mozilla.org/firefox/collections/mozilla/bookmark-managers/
Otherwise, I think you would be looking at a manual workaround. 
If you remove the label from each bookmark in your toolbar, that should make them icons-only.
This is something which you would need to solve with custom CSS in your profile’s userChrome.css. A Firefox 57 compatible add-on will not be able to affect this, but it should be a relatively easy addition to userChrome.css, as it sounds like all you want to do is hide the text label.
This is true. However, userChrome.css is very brittle and can cause problems down the line.
For more information, see https://developer.mozilla.org/docs/Mozilla/Tech/XUL/Tutorial/Modifying_the_Default_Skin.
Yes, userChrome.css is just a brittle as a full theme was: It’s at the mercy of Firefox not changing the DOM structure you’re applying the CSS to. Applying such CSS can certainly cause problems, even make the browser, or parts of it, unusable.
A significant difference between doing such things yourself in userChrome.css and using someone else’s full theme is that you don’t have someone doing the work for you of making changes/testing in new versions of Firefox, nor is the work you’ve done easily distributed to other people. However, by making the changes yourself, you should know that you’ve made the changes and be able to watch for issues in new versions of Firefox.