These times sound right. The bus time seems very realistic.
The reason the monorail takes so long is the various waiting times. You will wait for the monorail to arrive. And then at each stop where you don't get off, the monorail sits at the station for several minutes -- monorails wait a few minutes, unlike a subway or commuter train that gets in and out of a station as quickly as possible. So after you get on at GF, you will pause for a little while at the MK station, then again at the Contemporary station. Then when you get to the TTC, you'll need to get off the monorail, go over to another platform and then wait for the Epcot monorail before riding to Epcot. I can easily see how that could take 42 minutes.