Thank you for this very nice walkthrough. I think there is one simple mistake in the steps of "All Unicorns and Rainbows" achievement as you have no option "Follow the trail in the grass" after you press on the knobs in the correct order. Someone has already published a guide with the correct steps
here so you do not need to check your steps from the start. Also, saving the game during the play-through to obtain "All Unicorns and Rainbows" achievement is possible and will make obtaining the last two achievements faster.