The properties section in Part Edit/Metadata doesn’t seam that good. You can pull a CORE part into a view and change voltage, power, etc - if it has it - in Inspector, but when you save that as a new part some of the options where you could change the value in the CORE part become fixed and not enter-able in the made part. Basically you can grab the CORE Zener and change the voltage and save it as a new part, but it is now fixed forever to that voltage, unless you totally remove the whole voltage category in FZ Edit/Metadata/Properties and have nothing. Unfortunately you can never add anything back that will do anything, just a fixed value.
The reason why it’s not good is, imagine you make 5 different length Zeners and want to share them, well you have to make 5 different length Zeners, plus 5 different length Zeners for every voltage, power, etc. It seams that FZ only allows a specific part, not a general flexible part.