Hi @PSterkenburg. I don't know of a way to separate alias' in an inbox if they're all feeding into the same one. As far as I understand the reporting, it's based on the inbox, not any alias that's feeding into it. @karstenkoehler may have a different experience and answer, or someone else @BérangèreL tagged, perhaps. But as I understand Service Hub, that sounds like it's beyond the standard capabilities.
Did my answer help? Please "mark as a solution" to help others find answers. Plus I really appreciate it!
I'd recommend supporting the Idea with an upvote and explaining your use case in the comments.
Our product team uses that forum to collect ideas on how we can improve the product for our customers.
Product pays particular attention to the top voted ideas & takes them into consideration along with other feedback channels as well as their own vision to understand what features will be most valuable.