I wrote some info on a couple JPEGs using Windows File Explorer. In Explorer, I wrote info on the "Comments" and the "Subject" tags. However, when I import the JPEGs into Adobe Lightroom, I can't find the info I wrote. Does Lightroom not support this metadata?
Jeffrey Friedl's Metadata Viewer plugin for Lightroom may prove helpful. It should provide you with a way to work with the fields that Windows allowed you to add your information.
Windows seems to write this info into EXIF tags of it's own choosing. E.g. if you enter information into Windows Explorer's "Comments" field, this gets added to the EXIF metadata in the image using an EXIF Tag of "XPComment".
The Exif 2.3 standard does indeed detail these tags (all prefixed with "XP") and indicates them simply as "used by Windows".
Lightroom doesn't recognise this EXIF Tag (based on my brief testing on Windows 7 and using LR6.3 & IrfanView 4.38 to analyse EXIF Tags).