Bonita portal shows time relative to UTC
This is a known limitation of Bonita Portal. Today the computer date is used as a reference and not your browser timezone.
Which means that if Bonita has been deployed on a different timezone (GMT, PDT for example), then the user won't have the expected hour shown.
That's why you have noticed inconsistencies. As there is a feature improvement request open, I advise you to open an issue in JIRA Community to track progress on this issue.