Found on WinMe-Ja using 07-08-10-trunk and 07-09-05-branch. Steps: 1) Install new build and create new profile. 2) Launch browser. 3) Go to View>Set Language/Region>Download More and download JP pack. 4) Close browser. 5) Start Profile Manager and create a new profile. Do not change to Japanese region. 6) Launch browser. Sidebar and Bookmarks are set to JP region, but Search and Throbber are still set to US region. Note: This does not happen if the DE region pack is downloaded instead. Also, this bug only affects new US profiles. Once the JP pack is downloaded, any new US profiles will contain JP Sidebar and Bookmarks; if a new DE region profile is created, Sidebar and Bookmarks will be correctly set to DE region even if JP pack was already downloaded.

This problem no longer occurs on branch as of 07-10-05-branch on WinMe-Ja. Still need to check trunk build. There is still a problem where new or migrated JP profiles contain JP Sidebar and Bookmarks only; will file a separate bug for this.

Filed bug 90281 for the problem in JP profiles. The original problem in this bug had to do with US profiles.

What's timestamp of your regjp.xpi? If it is from n6.1b1, then, it is a known l10n problem. It will not happen in RTM build. I am closing this one unless you can reproduce it with a valid compatible build & langpack.

Verified on US Win 07-18-05-branch and 07-18-06-trunk builds using JP Pack from JA Win 07-17-05-branch.