lomiri-online-accounts successfully cross builds a broken package. The
location for hosting QML plugins uses the build architecture multiarch
tuple and therefore the resulting packages are unusable. The root cause
here is using the build architecture qmake for determining the location
of QML plugins. Debhelper supplies -DQMAKE_EXECUTABLE=... to CMake
projects so just using that variable fixes the problem at hand. I hope
this approach is suitable for upstream and am attaching a patch for your
convenience.

Helmut