Just to be sure that this is clear: there is no circumstance under EPCRS in which the employer will make an after-tax corrective contribution.
The calculated ADP is a combined ADP for all deferrals (pre-tax and Roth). In your fact pattern, the participant gets one corrective contribution of .5625%, all it pre-tax. Not .5625% for pre-tax, and another .5625% for the Roth. It does not matter if the participant would have elected to make his deferrals as all Roth or all pre-tax, or a combination - there is one corrective QNEC and it is all pre-tax.