I had the same issue, and followed aspergerguy’s suggestions, after that mine worked.
Please pay attention to the description in the Jolla guide ( Removing Android AppSupport | Sailfish OS Documentation ) for clean removal of appsupport, you need to remove f-droid, Aurora and Here before removing and reinstalling appsupport, otherwise appsupport won’t be completely removed.
To be sure everything was removed I also did the “brutal way” following the mentioned Jolla guide.
Obviously you also need to remove the installed versions of MicroG.
After reinstalling appsupport I installed F-droid, added the MicroG repo and installed the MicroG apps. Now I was able to tick all boxes in the Self-check, and Signature Spoofing Checker turned green.
However I still have issues with several android apps which complains there is no play services, so even though MicroG appears to be working some apps do not work with MicroG on the C2, they work fine on my XA2, only one of the are also having problems on my 10iii.
It is a bit annoying as some of the apps not working are Panasonic comfort cloud which I need for my heatpump, also Easypark and Parkone parking apps, which are badly needed i Copenhagen does not work. And obviously public ID-apps still complains the the phone is rooted and jailbroken.