Since there are a lot of European users I think the possibility to offset airtime is a valid request to get the correct time in airing tab.
NZB360 uses the service's API to retrieve this information. You want SickBeard to implement the offset, not the app. Cause what good will this do if SB wouldn't show the same times ?

You need go to their Github page and create a ticket there. If they find it useful and apply it, then NZB360 should show the 'correct' airtimes.