Cross compilation of KDE Appplications is a already proven way to provide stable releases for umbrello (see https://build.opensuse.org/package/show/windows%3Amingw%3Awin32/mingw32-umbrello-installer) and other packages (like kmymoney). The advantage is that no proprietary Windows system/licenses are required. To make KF5 releases similar support is required.
Cross compiled KF5 framework releases are developed at sub projects from https://build.opensuse.org/project/show/home:rhabacker:branches:windows:mingw:win32 https://build.opensuse.org/project/show/home:rhabacker:branches:windows:mingw:win64 e.g. https://build.opensuse.org/project/show/home:rhabacker:branches:windows:mingw:win32:KF565 https://build.opensuse.org/project/show/home:rhabacker:branches:windows:mingw:win64:KF565 Thee previous releases is located at https://build.opensuse.org/project/show/home:rhabacker:branches:windows:mingw:win32:KF547 https://build.opensuse.org/project/show/home:rhabacker:branches:windows:mingw:win64:KF547 Builds ready for releasing are submitted to https://build.opensuse.org/project/show/windows:mingw:win32 https://build.opensuse.org/project/show/windows:mingw:win65 To reduce the required effort, not every version of the KF5 framework is released.
Stable release are developed at https://build.opensuse.org/project/show/windows:mingw:win32 https://build.opensuse.org/project/show/windows:mingw:win64 and snapshots at https://build.opensuse.org/project/show/windows:mingw:win32:snapshots https://build.opensuse.org/project/show/windows:mingw:win64:snapshots