We deployed JIRA 3.41 on weblogic 8.1 SP3. We followed your instruction as given in the following URL
"http://www.atlassian.com/software/jira/docs/latest/servers/weblogic.html" including Character Encoding settings.

After user modifies the user locale as Japanese(Japan) in the Update User Preferences page, the japanese character in jira web page are displayed as "?" characters

Thanks
sundaram.s.s