The description for the latest Audio Cleaning lab says it has 8 tracks but there's little information on this. Can you overdub on tracks 3 thru 8 while listening to the 2 basic tracks and have them in sync?
SFACL3 is not a "multitrack recorder" so no, it cannot be used in the way you describe, sorry! I just checked this on my installation of the product and, with an audio file on tracks 1 and 2, selecting to create a new recording on track 3, that "new" recording is placed at the end of the existing recording, I can find no way to "force" it to be started and placed at the beginning of track 3. So, you cannot playback and hear the existing track(s) whilst adding the new one.
Since the app is already set up for 8 tracks, my guess is that it would not take a whole lot of reprogramming to allow synced overdubbing. If this were done, it would turn the program into a full DAW.