QML map projection missmatch.

[bodyakho]

Hi, i'm make some map based windows application on qt5 qml.
I'm create my own geoservice for qml map thats fetch map tiles from Google and work with offline tiles.
Next step is add Yandex as map tiles providers for this geoservice. It's done.
Problem it's different projections system. Google maps tiles (earth as an sphere) and Yandex map tiles (
earth like an ellipsoid). So Mercator in qt qml map is support google like model.
Question is can i somehow switch Mercator to another system?
If found interesting enumeration in qt private header qgeoprojection_p.h:

    enum Datum {
        DatumUnknown,
        DatumWGS84,
        DatumSphere
    };