I found my error - my pnts-file is from Feb. 2016. In meantime you have changed the Format completely and it is not backward compatible or i don't know in which way (version number ?) !
The pnts-format is completely new with featureTable and batchTable ....
and on the other Hand I have correct my tiles.json to tileset.json (boundingVolume, Region).
So I have to convert my pnts-file for the new Version !
You mentioned existing converter programs - one such program is Entwine, which supports 3d-tile output and is highly scalable (into the billions of points). The source repository is on Github at connormanning/entwine. Some public sample tilesets are at cesium.entwine.io, and build instructions can be found here. Maybe it will be useful to you.
Yes the original point cloud format has changed significantly since you last used it. Since it’s all still a work in progress we don’t support backwards compatibility with the old format. I hope the conversion process goes well.