It seems that in the specific version of Paymenter you are running, the theme update command has been removed or deprecated. The system likely now auto-detects themes just by scanning the folder, so you don't need to "register" it via the command line.

Since the cache clear (view:clear) didn't fix the missing descriptions, and the update command doesn't exist, we can confirm: The theme developer simply didn't write the code to display the description.

As a Software Engineer, you can fix this easily by editing the theme's HTML