I would also like to see JRiver populate at least a single library field that indicates if the file is HDR or not as it would potentially be useful to use for automatic zone switching. There's a fairly long standing defect in MadVR where it stays stuck in HDR mode once you play a HDR file, requiring a reboot to get back to normal. The workaround, for now, is to use the JRVR instead of MadVR, but it might be ideal to be able to use Zone Switch to use a JRVR zone for HDR material and a MadVR zone for non-HDR material, at least while development continues on JRVR. Having to use external tools to populate this data really isn't an ideal solution.
In my case, the most important thing to know is if the media is going to switch my output to HDR when the media is played (either with MadVR or JRVR), so I would be satisfied with a boolean field. Ideally, it would be nice to know the format (HDR10, Dolby Vision, etc.) so icons can be displayed in Theater View, but that's a much lower priority, at least for me. I realize that Dolby Vision playback isn't supported on PC's yet.
Given that JRVR will supports switching the HDR mode, it seems as though it ought to be possible for the JRiver library to automatically obtain at least the boolean field to indicate the file is HDR.