Tweak Tool will indicate which extensions are not working. A mouseover should generate a tiny explanation. "Outdated" is used to indicate versioning problems.
An identical capability is available at extensions.gnome.org.
Correcting the Gnome Shell version in metadata.json has been hit or miss for me. It seems to be important to be precise. I.e., if you are running 188.8.131.52, use that, not simply "3.8".
Unless an extension is available in, and installed from, a repo, I'm pretty sure that updates need to be installed manually. I usually disable the extension, then go to extensions.gnome.org, and reinstall it. If that doesn't work, I delete the extension manually and try again. This is an area that definitely needs improvement. Gnome seems to like having the extensions around but also seems reluctant to fully embrace and take responsibility for them.