Page Headers on User Profile/Author Pages

No problem!

Super awesome filter :)

Leo, do you have a function snippet that will work for the date archive pages too? (for showing a particular page header)

That depends on if you are referring to all the date archive or just month etc, this should help:
https://codex.wordpress.org/Conditional_Tags#A_Date_Page

Yes! This worked for ALL date archives, thank you so much :)

add_filter( 'generate_page_header_id', function( $id ) {
if ( is_date() ) {
return 546; // ID of the Page Header to use.
}

return $id;
} );

No problem :)