Did I understand correctly that you have the heights in CGVD28 (HT2_2002) and want to convert them to CGVD2013(CGG2013a) and compare them with those in Emlid Flow?
If so, please select CGVD2013(CGG2013a) in Emlid Flow.
One more thing: I noticed that you are using a Legacy CS from our registry. I suggest choosing the CS without the legacy tag. The easiest way to do this is to type in the country’s name when searching for the CS:
Choosing the CS from our updated registry (without the legacy tag) will ensure that the points will be consistent with what you get from your country’s surveying transformation tool.