Hi…
I am thinking that’s not optimal to use the organizer logo as featured image. Mostly the organizer is always the same (at least on my website, but I think I am not the single one). If you share your event in social media the user only see the organizer logo, but this isn’t the interesting thing. The user needs to be informed what the event is about and for this use-case its much better to show a specialized banner for the event not the organizer.
As a work around I use the event banner as organizer logo. But this isn’t far away to be ideal. Perhaps you can add to fields: one for the organizer logo and one additional for the event banner aka featured image.
Thanks in advance
Thorsten