Maybe there is a reserved Tasker variable that contains the mode you are currently in. This would certainly be the easiest and fastest approach.
But you can also check out the Tasker plug-in CalendarTask. While it doesn't seem to offer what you need out of the box (maybe the ctavailable variable it provides will work though), it is a very useful plug-in and you can query all or a specific calendar and get a bunch of variables returned.
You could then add a unique identifier to the event title, description or any other field you can query. For example, when creating an event instead of selecting the busy option, you could write "Busy" in the description field or simply "0" or whatever else you like.
Then create a profile that triggers when an event starts and link it to a task querying the description field of that event to determine if you would like to put your phone into silence mode and take it from there.
Clem
https://tasker.joaoapps.com/userguide/en/variables.html
Check out the "Tip" in this section - this might contain the info you are looking for:
"""
Calendar Event Title / Descr / Location
%CALTITLE / %CALDESCR / %CALLOC
The title, description and location of the current calendar event, if there is one. If there are multiple current calendar events the variables refer to the shortest.
Tip: find other details about the current event(s) using the Misc / Test action, specifying %TIMES for the data.
"""
Clem
I can vaguely relate the above to Tasker's "State Entry" dialog for Calendar Events:
There I see fields "Title", "Location", "Description", "Available" the first three of which - I guess - correspond to %CALTITLE, %CALLOC and %CALDESCR above. It is unclear to me to what value the "Available" field refers to.
And - pardon my ignorance - I don't understand what is meant here by "find other details using the Misc / Test action ...".
Could you elaborate? I am an IT guy but definitely not a Tasker Guru...