It seems that the function Calculate time difference, in Global Settings->Regional does not work, or may be I'm doing something wrong.

I tried in my own 2.4.7, and in http://demo1.b2evolution.net/stable/admin.php?ctrl=locales, but the link http://demo1.b2evolution.net/stable/admin.php?ctrl=locales# just show 0 (zero). Even when here in Sweeden it's 09:56, and the server time is 12:56