Solution
You cannot programmatically change the type (the strings) of an enumerated data type, just as you cannot programmatically change an integer control into a double or a string control into a path control. The strings in an Enum are a part of its data type and thus can only be changed during edit time. It is possible to read the strings of the Enum through a Property Node, but you cannot write them using a Property Node.
If you choose to write to the Strings property of an Enum during runtime, you will see
Error 1073 occurred at Property Node as shown below: