Just as an FYI I have forked and fixed up the Cesium Drawhelper so that it works with the latest version of Cesium. I also added in drag functionality for Polygons so that you can move them around.
If anyone is keen to help it would be much appreciated! I am quite busy with other projects, so just updated this well enough to use.
If anyone notices any problems feel free to raise a ticket on github, or preferably have a go at fixing it yourself!