Custom integration of calendar state

Hi guys,
Could you please tell me how my calendar issue should be solved.
I have implemented custom integration extending calendar entity. It fetches events from csv file on the web and translates it to events. Everything looked ok until I checked for calendar status.
As those data don’t change much I set SCAN_INTERVAL for 30 minutes. But it turned out that also status of calendar is updated in same interval so I get state change with like 9min from event start time:

I have implemented workaround by changing SCAN_INTERVAL to 20 sec and skipping http request if last one was within 30 min but it does not seem correct.

Is there better solution for that? Is there STATUS_UPDATE_INTERVAL or something similar?

If you look at what the calendar integrations in core do they typically have one interval for reading data from the data sources and another much shorter interval for updating the entity state to catch the start of an event.