Restoring a system at 13.11.16-19 from a 13.11.16-15 backup?

I am attempting to restore a system that is currently at 13.11.16-19 from a 13.11.16-15 backup. Is this not allowed?

It will probably work fine. In the (unlikly) event that you get locked out of the GUI in the process of the restore you can upgrade modules to current from the bash prompt with:

fwconsole ma upgradeall