OK, so I have now looked into this bug and what these messages mean. TLDR: comment out those lines and that's what the next release of snmpd will have.
Those tokens are for the DISMAN event handling. In effect, they are like a macro that turns on a lot of event messages for a system such as low disk free. The systemd unit file and the init script exclude both the mteTrigger and mteTriggerConf modules. These modules (one or other or both) contain the tokens that you see in the log. Turn off the modules snmpd doesn't know what those lines mean. So why not remove the configuration to disable those modules? The modules require the DISMAN SNMP MIB. In effect a file that converts the textual version of an SNMP variable into a number. MIBs in the old days have the same license as the RFC which is non-free. For newer ones, they are licensed under the BSD license but not the old ones, unfortunately. The options are: 1) Comment out those lines in the configuration file; or 2) Download the DISMAN MIBs, Debian cannot have them in main due to license problems - Craig 1: https://wiki.debian.org/NonFreeIETFDocuments