Hi Benny @himbl,
It is true that with the EyeX the sampling frequency will vary around a few Hz about the 60Hz average during tracking. The tracker is not designed for scientific use, so limiting the variation has not been prioritised for this eye tracker.
The Tobii Pro range of eye trackers however have a more stable sampling rate to aid in research fields.
With respect to the time column, this represents the internal clock on the EyeX TET server and is designed for syncing between multiple computers, so not useful for this purpose. The computer time should be used.