DO NOT TURN ENGINE BACKWARD! SHIT HAPPENS!
Just to share about my personal experience today.....I did an overhaul to a Honda K24A2 engine on a Acura TSX, replacing the timing chain tensioner and clutch. I and my friend were struggling to get the crank pulley off: my friend use a prybar to lock the flywheel side, while I try to loosen the crank bolt. My friend slipped a few times, inadvertently rotating the engine counter-clockwise, just a few times.
We finish up and put everything back together, and start the car. The car ran like shit, and threw an engine code of the VTC sensor (P1009). We thought it must be impossible that we messed up the timing, but we checked anyway, and the timing was off by like a few tooth. We believe when we turned the engine backward while undoing the crank bolt, the chain lost tension and skipped a teeth or two, and that was while the chain tensioner was on!
My take on this is, yes, the engine is engineered to be turning clockwise, that there is a tensioner for the timing belt/chain for it to turn clockwise. If it turn backward, for whatever reason, there is no tensioner for the timing belt/chain, and shit can happen.