Is it any coincidence that celebrities were added about a month later?
Yes. I'm assuming that
Whew!'s ratings were always trouble (as has been mentioned before, one of the show's biggest problems was an overwhelming format that required too much concentration to keep up with). I'm also assuming that the ratings didn't drop suddenly and significantly because of a string of Gauntlet losses, which a viewer would only notice if they watched the show every day.
Friday's episode was the start of a new taping day. They finally fixed that light bulb, there was a new split-screen shot the director was trying out, the list of writers in the credits got much longer (I wasn't able to compare the names, but it looked like the researchers may have received a promotion?), and the questions in the bonus round went from "the contestants have no hope of winning" to "there's at least a small chance a contestant could get close to a win."