Created attachment 8705 tooltip says Save and not Backup As applying panel presets affects all settings in the dialog, it should be put at the top of the dialog and separated from the reset of the controls by a slider. Also having it at the top ensures that it is the the most likely first thing that a user will attempt to change when opening the dialog. In addition to moving it to the top, having a 'Presets' label before it will better clarify what the button is doing and changing the button label from 'Backup and restore' to 'Apply and save' make it have a similar label to the tooltips on the buttons in Xfce Panel Switch.
Created attachment 8706 patch
Simon Steinbeiss referenced this bugreport in commit a4901785c96375e2a79840361b4ccd61209e568d prefs: Improve position of panel profiles button (Bug #15657) https://git.xfce.org/xfce/xfce4-panel/commit?id=a4901785c96375e2a79840361b4ccd61209e568d
I went with a slightly amended version of your patch, but it's still very close to your suggestion. Thanks for the report and the patch!