That’s some great work in investigating the Mac ports of AGI games, Steve.
According to the credits for the Mac versions of KQ1, SQ1, and SQ2, the Macintosh version were done by “Mark Langbehn of Fairfield Software”, so that sounds like the Mac ports were contracted out.
Speaking of Mac versions of other Sierra titles, it is interesting to see how few of the SCI0 games were ported to the Mac (SQ3 is the only one which immediately comes to mind). I read that Hero’s Quest was ported to the Mac, but that may be incorrect, or might be confused with the VGA remake which was ported to the Mac.
However, Sierra did a pretty good job in bringing quite a few of its games of the first half of the 90s to the Mac (many which I own).