Not use the Proforma does it.  If it really did do that there would not be a need for an input field for 2019 Earned Income unless as an override and override is not indicated on the box.

Regarding the automatic calculation I was now reviewing notes from a tax conference I attended.  The instructor uses Drake Software and his hand out states. 

"To give taxpayers the largest credit possible, Drake Tax 2020 will calculate both credits, using both prior-year and current-year earned income, and automatically determine which results in the larger credit." 

Shame on Lacerte for costing more but delivering less.