Certainty is not approved for use in cool season turf and will absolutely damage or kill bluegrass and fescue.
Well I know really nothing about the technical stuff of the chemical. All I know is I bought the stuff and we had the guy apply it twice a year from probably 2011-2014 and have put it on 1/year 2015-current. You could easily tell that the grass was under stress for a couple weeks but we have never had anything die - except the wide bladed stuff. We are in central Iowa and all four of our yards are local sod so I assume it is bluegrass.