@rvr thank you for the report. It shows that there are two instances of Finder process running PID #32522 and later #32578. It seems that the first one is still alive when the TotalFinder’s agent gets request to inject into the second one. Thus the message “already-injected - nothing to do”.
I have to investigate how is this possible. Likely scenario is that Finder gets restarted during system startup and special timing causes TotalFinder injection while old instance is not fully terminated and new instance already requesting TotalFinder injection.