This is a bug for us.

This is similar problem against Bug 1095465 as follows:

Bug 1095466 - IDM Apps does not support localized time for requestSubmissionTime token in Notification Templates

We recognize there is no workaround for that problem.
Though this bug is Enhancement request, we need to fix this bug first than other bugs that has workaround.

So, could you set the bug also to IDM 4.7.2 for target milestone?
Identity Applications can display Japanese date and time correctly via web browser, so I think you can fix it easily.

This is not enhancment.