OK, I can confirm that in 3.70~6 beta that the power factor registers above are readable for my Carlo Gavazzi EM530, except that L3 and Total Power Factor are being read as 0 probably due to my having US split-phase.
A power factor of 0.79 is read as 790 in int16. It is definitely signed, meaning that a negative power factor means power is being exported on that phase.
I am assuming when you ask for Watts that you get actual power.
To get apparent power in VA, divide watts by the power factor.
Note that I am not a NodeRED guy, I am reading the ModbusTCP registers directly from the Cerbo.
EDIT: I see the following in the 3.70~5 release notes from MVader.
You may not want to put a beta on a production system.