Calling object function in visual builder

Summary:

We have an object function that will calculate the country region based on the selected country, and we would like to trigger it every time that the country field was changed,

currently we have this formula field in classic UI, however in the redwood UI it is not working until you saved your record.

i notice that redwood ui has it own calculated field and we would like use it, so that user can see the calculation in real time.

our object function used viewcriteria as the result will be fetch from other object based on the country value.