A one-two punch: Windows 10 update KB 3124200 and Office update 6366

Users who install Windows 10 version 1511 build 10586.36/Cumulative Update 6 and Office patch 6366 may be in for a double whammy..
As noted Microsoft Press author Ed Bott has observed, Windows 10 patch KB 3124200 does not in fact destroy Word customization as originally reported. That damage was actually done by the Office 6366 patch — specifically, an update to Word 2010, 2013 and 2016 — that many people installed simultaneously with KB 3124200. You can find manual repair steps for the Office 6366 patch here. Info World regrets the error. This post and its title have been edited to reflect the correction.
The patching situation with Windows 10 has gone downhill in recent weeks. While it originally looked like KB 3124200 (cumulative update 6) solved the major Wi-Fi problem introduced by KB 3116900 (cumulative update 5), it now appears as if KB 3124200 is also causing problems.
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Radu Tyrsina at Windows report has amassed a list of more than a dozen problems with KB 3124200, including the following:
Install failures, which have become very common with cumulative updates. Usually, but not always, frozen installations can be fixed by installing the patch manually.
File Explorer, Calculator, Store, Calendar, and/or Maps won’t work.
Outlook won’t open.
Errors 0x80242fff, 0x8007000d.
Installation failures are particularly bothersome on Windows 10 machines because Windows Update continues to slam its head against the wall, downloading and installing the impossible patch over and over again.
At the same time, Microsoft has released Office update 6366, which wipes out your Word customization. Somehow the installer takes it upon itself to rename the Normal.dotm file to Normal15Pre.dotm, Normal Old. dotm, and/or Normal.dotm.old.
That may sound like a minor problem, but it effectively breaks nearly any customization you have in Word. Auto Text entries, macros, default template settings such as margins and fonts, custom styles, envelope return addresses, auto correct and auto format settings, and much more get trashed.
Microsoft has a new article, KB 3129969, that steps you through the process of fixing the problems introduced by Office update 6366.