Is there a way to overlay the file name of the current wallpaper in 9.7.2 beta 8?

Yes, there is.

Go to Desktop Wallpaper (right-click system tray icon).
Click on desired monitor.
In lower-right section of screen under "Monitor Settings" click the Info tab so there is a check-mark in the box.
Press the "Add Info Tag" button below, highlight Wallpaper and select File Name.
Click the Apply button.

Lots of other info options available. Select placement of the tag using the little monitor in the lower right.