Hi Miguel,
I was unable to add a GenericTile to a TileContainer.
It should have worked as the aggregation says that the tiles have to be a sap.ui.core.Control which is also true for GenericTile.
However, adding it directly to a page works.
StandardTile works fine with the TileContainer.
To add a GenericTile to a TileContainer, I wrapped it in the sap.m.CustomTile as its content and then added this CustomTile to the TileContainer. That works for me.
Regards,
Yogesh