And here I just got the old preserve_entities patched version compiled and running on Windows!
Oh well. At least it's fresh in my mind now, so building the new version shouldn't be much trouble.
The Windows nmake makeinstaller target needs a little tlc, but the changes that need made are relatively small, so I'll wait to see when/if your changes are pulled into the main before submitting a patch for the src/Sigil/CMakeLists.txt file. A few of the QtLibs have been added/dropped from the early days of Qt5 (and the icu libs have been updated.)