In Bonita 7.1, the timezone display was still incorrect. Though it fixed the problem of displaying correct local timezone according to locale, but it does not follow the timezone filter specified by AngularJS. The root cause was because it was still using Angular 1.3.x which does not support timezone offset.
I found the UI designer embedded AngularJS in WEB-INF/classes/static/js/vendors-xxxxx.min.js. Is it safe to replace with version 1.4.2?