I got a high brow lecture about how you need a scope to determine if the echoes are really synchronous as light travels faster than sound..
That's complete rubbish, over short distances the relative speed of light and sound isn't going to make a difference.
The easiest way to see if the delays are in sync is to get a simple drum loop with a beat on each quarter note, run that through the pedal, set the pedal to one repeat, set the taptation to quarter notes and tap in time to the beat. That should give give a delay time equal to a quarter note so the delayed version of one beat will land on the next beat. You can easily hear if that's in sync or not.
Madbean has a chip set that works fine but it is a much older Taptation chip. Go figure.
That won't have anything to do with it, there's virtually no way the taptation chip can be out of spec. In theory the firmware could get corrupted but the chances of that happening to multiple chips in a way that made them all appear to work but set the delay too fast is practically zero. I suppose it's possible at some point the firmware Aron is burning the chips with got changed but then none of them would work properly.
Your best bet for figuring this problem out is to find someone with a working setup and and sent them all your parts and get them to swap bits out until the problem appears.