My second link takes you to a WC thread where
Edouard links to an OWC page that details a couple of ways to downgrade. Here is a perninent comment in that description:
With the right preliminary preparations in place before you perform an upgrade, downgrading can be fairly easy, though a bit time consuming. Without the proper preparations, downgrading can be difficult, to say the least.[emphasis added]
should you attempt the downgrade, this is the OWC page:
macOS Reversion: How to Downgrade from High Sierra I will only suggest that,
personally, being able to automatically add a tweet, is not enough of a concern for me to downgrade. Of course, I have not even gone to
macOS 10.12 Sierra on the mini that is running my WC app and I am still debating upgrading to
macOS 10.13 High Sierra on this iMac.
"Good luck, young Will Robinson!"