I’m afraid I don’t think it’s you. As far as I know, missed & missedprc are completely undocumented. Trystan told me in a PM they are the count of “missed” messages - presumably not received, maybe including corrupted and therefore unreliable, messages. I know no more than this.
MSG is indeed a count of the messages originated at source, and rssi is received signal strength indicator - a common term in radio circles (less negative is good - a stronger signal).
For the record:
Vrms - root mean square voltage (the usual measure of your supply voltage).
P1 etc - average power over the reporting period in watts.
E1 etc - the accumulated energy over all time (or since last reset) in Wh.
T1 etc - the temperature in deg. C. Note values 300 - 304 are error values, documented in emonLibCM User Doc.pdf, available here https://community.openenergymonitor.org/t/emonlibcm-version-2-2-2/ )
pulse is a count of pulses detected over all time (or since last reset).