Qt5 on Windows uses a different runtime path layout as other required open source packages. To fix this either it is required to patch Qt5 to follow standard unix path layout (data in share, modules in lib and so one) With KDE4 it is simple to generate a Windows package for example from a linux spec file (rename *.so to *.dll, dll files are located in 'bin' not in 'lib' and so on), but now you need to know exactly which dll or data file is loaded by which component to decide where it has to be installed.
This has been added to Qt 5.9 and Qt 5.11, see for example the patches at https://build.opensuse.org/package/show/home:rhabacker:branches:windows:mingw:win32:Qt511/mingw32-libqt5-qtbase