Actually the parameter panel is build using values from the variant specification XML.
The variant specification XML stores the choice name and not the choice value of a numeric option, so there is not any possibility to get this value from an expresión of a parameter.
My suggest is add the value of a choice of a numeric option into the variant specification XML and add a function to get this value into the expressions of a parameters.
Add a file to reproduce the issue
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.