In the HereSphere web API view, look for the cogwheel in the bottom right corner. Click on it, then enable overwrite tags. That might be the reason why the start and end times aren't updating. Also, make sure to disable then reconnect to the web API to scan the library again.
There's a free demo available on steam, which should work fine for adding tags and writing hsp files. If you don't connect a headset, it'll launch in desktop mode, which allows you to control the camera with your mouse cursor. There's just a ton of other priorities I have at the moment, so maybe these workarounds can be of use.