It looks like the service is running from /etc/systemd/system/mec.service, not the one in /usr/local/MEC
I just tried each of the three pico confs in /etc/systemd/system/mec.service. It does look like the changes are getting picked up now, but my pico is still not making sounds. Progress, I think.
It looks like blokas is running an instance of MEC with its own .json file as well?
root 504 0.0 0.0 1940 416 ? S 03:34 0:00 /bin/sh /usr/bin/mec /etc/mec-blokas.json
root 510 0.7 0.2 43592 2632 ? Sl 03:34 0:06 mec-app /etc/mec-blokas.json
Maybe this will make more sense to me after I get some sleep.