"Top posting" (writing the answer above the text that's being replied to) is literally industry standard behavior.
Also, I don't think you've really cleared out any confusion. Now, how exactly can dovecot log to /var/log/dovecot/ without (postfix) throwing errors? Because it clearly is for 2 out of 3 files as visible from the file sizes in my original post. Only the debug file is empty, but maybe nothing relevant enough has been found yet. There are entries from master, imap, imap-login, managesieve-login, anvil and various other processes in info and error. But the error messages from postfix still appear, also seemingly at least vastly slowing down emails being delivered to the users, if not bringing that to a complete halt. Only after commenting out these locations in 10-logging.conf the mails show up for the users.