Custom Telemetry - Custom Event for Bot

I know we can add custom telemetry for the Healthcare bot using session.logCustomEvent(<eventName>, <eventPayload>). But, I've noticed that it logs the custom event parameter "speaker" to "user" instead of the bot. So, is there anyway to log a custom event and set the speaker parameter to the "bot"? I can't find any documentation on session.logCustomEvent that takes in more parameters than the eventName and eventPayload. And, it messes up all my analytics dashboards when it thinks these customEvents are from the user.