Does anyone else think that in the Golden Goblet, the Dark Forest opened from the Jester's Court? When the girl completes the room you can hear the Dark Forest door sound effect. Maybe the wall wouldn't have been breakable like Alhambra/Theodora? Also, this run's layout was pretty difficult imo 
If we're going by sounds effects alone, then yes, the Dark Forest did open during the Golden Goblet run. By comparison, the low humming noise signaling the opening of the Dark Forest did not play during the Silk Sash of Mulan or Golden Pepperoni of Catherine de Medici runs, where we know the teams were able to enter the King's Storeroom. Still another sound effect played during the Missing Weather Maps of Charles Lindbergh run, where we also know the King's Storeroom opened but the Dark Forest did not.
As far as the intended path for Golden Goblet, I think that they would have been forced back upstairs either way. Given how runs from the same production day tended to share similar layouts and difficulties, it wouldn't surprise me. Take Silk Sash of Mulan, the run immediately prior, for example: Jessie and Steven had to go down the central shaft, up from the Jesters' Court to the King's Storeroom, and then back across the upper floor. Another thing I'd like to point out is that the half pendant for Golden Goblet was on the actuator from the Pit to Medusa's Lair, meaning that the Observatory was an extra room that did not need to be completed for this run.
And as for the temple guards for Golden Goblet, we know there was one in Medusa's Lair. The only unentered rooms were the Ledges, Dark Forest, and Secret Password. I suspect that the Ledges held a guard, since most Season 2 runs had a guard in one of the entrance rooms. Additionally, the upper left room never held a guard during Season 2, while the Dark Forest frequently did. For this reason, I believe the Dark Forest held a guard, meaning that that room was capable of being entered during the Golden Goblet run.