Not sure about mingw. I presume it would need some new build/project files, unless mingw can work with .vcxproj files directly? (Currently each platform has its own platform-specific project files [VS2017/XCode/CMake]) I can look into it in the near future if you want to open an issue on OpenWL.
I don't know much about Scintilla, but I looked at it once briefly and it seemed like there were various backends? So maybe by creating an OpenWL/DL backend? Seems like a lot of work, but again, I haven't looked enough into it.
