At time of writing this feature is still in Beta.
Currently, if you enable the Organization-Wide Email feature, if a user sends an email using an aliased email address Email Log v2 and Email Logs do not record who actually sent the email.
There does not appear to be even a context ID type field or lookup that is populated with information you could use to join to or resolve with another object. While there maybe some workarounds, the information currently isn’t available - so if you have been or want to use either object and the ‘from’ email to filter or otherwise use to identify the sender you will not longer be able to do so reliably with this feature enabled.
Please include/expose this data on the base object directly or via a lookup so this functionality is not lost.