I don't have a Japanese setup, but on my TG16 CD setup I have the system AV modified and region chipped, and the CD Dock RGB modified. The only issue is that CD audio will not come out of the TG16's audio jacks, but everything is good on the CD Dock's jacks.
So in your theoretical setup, I would imagine Svideo out from the PCE would be fine, but you'd have to use the IFU's audio jacks.