\By no means do I rank up there with college coaches but to me this sounds off. Sure, catcher is coming out of the hole towards third you gain a step or two there. At the.most physically demanding position on the field you have her sprinting to third, besides all the sprinting to backup first? What happens when it is a good sac bunt that is on the line 4 to 5' from the plate? Catcher runs by it and passes 3rd baseman coming to it? A push bunt, yeah that will work but a good sac bunt and your catcher will make a play on the ball leaving third open. IMO
Next practice put your best sac bunter up and tell her to put it down third and see what happens. Also, what happens on a bad bunt? One right in front of the plate. Will your catcher field and try for two, possibly missing both outs or will she throw to first leaving thirs open again? I just think this play works only on push bunts.
The catcher covers third if she doesn't field the ball. If she does, third baseman retreats to third. It just needs to be communicated.