The above DITA-OT 3.1 reference explains that to modify your labels you need to declare an extension point.
When using a customization directory, I tried included the extension point in my batch file.

When using a plugin, I tried to include the extension point as a feature in my plugin file.

According to the above reference, I should be able to modify all the strings called by the getVariable method.

The strings declared in the customized xml file, the reference claims, will now be available for the getVariable template.
If anyone has managed to modify the "Task Example" or "Task Result" labels using this method with DITA-OT 3.1, please share your secret.
Diane