Sheered Off Bolt Head in Engine

[PorscheServiceThen529Plan]

So I was just finishing off replacement of the water pump and LN t-stat, and when I was tightening up the bolts on the engine bracket, there is one smaller 10mm bolt in the center that I sheered off when tightening it, the 4 or so 15mm nuts tightened up just fine. What is the job of that smaller bolt and should I bother with an extraction job? Not much clearance and the sheered bolt surface is flush with the rear surface off the bracket so it still supports it, but does it have a separate purpose as a centering bolt? Any guidance much appreciated,

[creekman]

Can you drill a hole in the center of the broken bolt to use an extraction easy out?  At least since you just installed the bolt it should come back out fairly easily.  I guess you could remove the water pump so you could get at the broken bolt...  I've taken a small punch and a small hammer and rotated the bolt. However once you do that there's no turning back.  If you can get a right angle drill in there that would be my first choice.  If you do drill it be sure to use a center punch first, then start with a small drill.

[PorscheServiceThen529Plan]

I will add a pic to show which bolt. Its one of the bolts that hold the engine bracket to the engine. the more I think about it, the bolt that sheered was only 10mm and is in the center while the rest are 15mm nuts that do all the work holding the engine, so I am thinking that the 10mm one wasa centering bolt that i should have done first. It was not properly aligned because the bracket hole was a touch off center of the hole axis and like a dope I was hoping that tightening that bolt would realign it but the others were too tight.

[PorscheServiceThen529Plan]

So the one I sheered off is the Yellow arrow - centering bolt. (THANKS TO PELICAN PARTS FOR THE PIC I COPIED.) Wondering if that is really worth extracting if enough of it is out of the hole to pass through the engine carrier and act to line up the carrier. I do think its 1-2 mm off dead center does that matter? Tempted to loosen up the 15 mm nuts and extract the bolt and re-align perfectly, but not if its a waste of time. What do you think? thanks,