I think the better option would be to have two data set with localized and non-localized value. Based on which locale the application is using, the WHEN condition should evaluate and ask for that data.
So if French is being used then, a property should be passed and application should ask for the localized data.
You need to create field values for those or after loading the data from service, set the localized values onto a property. In the drop down based on user selection use the localized property or regular property value.