Are you quite sure that the Region 2/4/5 Mothra DVD has a unique audio commentary? While it's an obscure release, I can't find any record of Steve Ryfle recording a commentary with Ryuji Honda online. I would expect Sony to just reuse the one he did with Ed Godziszewski.
Updates: DVD Compare says it has the Ryfle/Godziszewski commentary. The back cover doesn't mention any commentary.