I have a similar setup to @MyForest, though I pull data from MelCloud and push it directly to EmonCMS without any intermediate files. I find that the fields in User/ListDevices has everything I need, including power measurements and flow temperatures.
I can mostly poll it every minute, though sometimes Mitsubishi’s server misbehaves and I need to drop to 2 minutes for a few days.
If you don’t have heat meters connected (aka MMSP) then some power numbers may be missing or estimated. Multiply HeatPumpFrequency (%) by maximum input power to get a good approximation of consumption. If you’re measuring these separately, then use those inputs insteads.