Yes, resource pools with the same name on different clusters is one of the problems that are still present in the script.
I'm working on a new version that should fix that problem.
Hopefully I will find the time to publish that in the coming weeks.
The spec.PowerOn is a apparently a catch-all error message for the CloneVM_Task method.
If the other problems, like the one with the resource pools above, are fixed I suspect this will disappear (I suspect).
Indicating mandatory parameters is a good suggestion, I will take that into account for the new version.