Not sure what you are trying to achieve, but usually if I need some variables to impact widget in editor, I use them in preconstruct event, which works similar to Construction script in BP.
ie let’s say I want to lerp the tint of the progress bar with Percent as the alpha - if you change the tint in Preconstruct event you will see the tint changing when changing Percent value.
But again, not sure if that’s what you are looking for?