I contacted support earlier in the day EST over a complicated issue. What does it mean if feedback is "open" ?
It means they have not gotten back to you or solved the issue
...any decision making about it. TER's standard is 72 hours for a response. They often are much quicker than that but you can never be sure. Just keep checking they will get back to you.
It's a mystery to me, but I think TER Admins are either in UTC or UTC+1, time zone-wise.
If you are in the US Eastern Time Zone, you are UTC-4 EST or UTC-5 in daylight savings time. If you sent your note at 3PM EDT, it was 8PM or 9PM in TER-land and they had probably left long before to enjoy their evening activities.
Your report remains "open" until they respond to it, probably in another 12+ hours (9PM + 12 = 9AM). I've had really quick replies but also slow replies that had fallen off their radar. I usually give them a few days before even thinking about re-submitting (depending on the criticality of the issue).
Although a TER reply renders the status of your note "Closed", you can still reply to that, thus re-opening it and maintaining continuity of the discussion