I think we've all ventured down a merry path that isn't related to the OPs question. The question as I read it just refers to notification 'sounds' not the cross profile notifications themselves.
I have just run a test while logged into a secondary user profile myself and experienced the following:
SMS, Signal and Whatsapp messages did not produce a sound or vibration.
Cellular, Signal and Whatsapp calls produced a sound and rang out as they would regardless of being in secondary user.