Edit: another example of something that should return back to the original time, and it does with timeapi off, but with /timeapi on, it goes back in time 10 hours, which i assume is due to my timezone's local time adjusted for daylight is GMT-5

Ack. This was harder to track down than I expected. There are quite a few API calls involved in converting between unix/system/file times, some of which apply offsets themselves, and the drop-ins can call each other in some cases. This issue has hopefully been fixed for the next version.