They move things in mobile UI a lot, so the docs might not reflect that. I know it used to look like on this screenshot, but I haven't had it in my Nightly for a while.

The reader view and translation buttons aren’t shown on all pages, just pages for which they are relevant.

I've tried German and French pages, languages for which translation is supported, but haven't seen the translate icon in the toolbar. I had to go through the menu each time.