Yes (see post above yours)-- https://www.delta.com/us/en/booking-...n-certificates

"If the primary ticket and Companion ticket are changed after issuance, subject to the fare rules of the primary ticket, there will be a charge for the fare difference of the primary ticket. Changes are subject to the rules of the fare purchased and are subject to seat availability. After travel has commenced, rerouting is not permitted."

You'll need booking inventory availability in designated classes for certs for new flights (LUTXV coach classes for Plat certs).