Currently the HSTS preloading check looks like this:
I'd suggest to also include HTTPS-Everywhere in the list as it also is a kind of HSTS preloading:
As HTTPS-Everywhere is open source (and it uses XML files for all added websites) and you can e.g. view a list of included websites here this may be possible.
BTW I really doubt that google.com is not preloaded in Firefox and Tor. Especially as these browsers even have Key pins for google.com preloaded it would make no sense to not preload HSTS.