This issue was raised in this thread previously: How to CC multiple email addresses in an automation. The original poster asked, “So just to clarify. Multiple email addresses cannot be copied on the same/single outgoing email through an automation?” The thread was subsequently closed without any response.
I do not think this fix should be excessively difficult, given that the more advanced email generation function already exists in Emails & Activities (where you can input the To and CC fields of a single email rather than BCC’ing multiple people) - we just need that interface in the integrations centre.