Those values are named "param_2" and "param_3" in Lua. I split param_2 and param_3 apart arbitrarily because it didn't make much sense for ratings to start at 64 and go to 72.
"param_2" corresponds to the monster's TW/EP/DC/EM/T/VT/IT rating. It is blank in the case of NMs because they use a message from the .dats that doesn't have a variable field.
"param_3" has an unknown function, but it is always 1 for check messages afaik.
These take different meanings when transferring a "Time Remaining (XX:XX:XX)" message when you try to use a JA before it's back up.
When analyzing the action/action_message packets, it's necessary to remember that SE is mostly only sending the information that we need in order to coordinate the animation, log message, and client changes. Out of all the crap I've looked at trying to make something that mimics the normal chat log, I have only found three values that I didn't expect:
1) Monster Level (out of left field)
2) Gauge Rating (depends on CHR, doesn't depend on MAcc. May be an exact measure of your resist rate. I think I display this.)
3) Spell Recast (I just didn't expect this)
There is really only one field left where I have 0 idea what it does ("inner unknown"). There's also a mysterious missing Category, 10, which probably exists for JA "Readies" messages that we don't actually have because you don't "Ready" JAs.