Quest Bug - A Song in the Silence - help?

[Skyrim Mod Developer M7 (Ret.)]

Quest bugs - A Song in the Silence
The bedroom door inside the 2nd Level of the Ketaron Dal'Geyss Estate won't open (not locked) and the door on the balcony also won't open when I press "E" to open (Teddy bear room), and even with the key. So I cannot proceed with the quest. Also some "Help" features are in German.
M7. 2019.

[Skyrim Mod Developer M7 (Ret.)]

https://en.wiki.sureai.net/Enderal:A_Song_in_the_Silence
M7.

[Skyrim Mod Developer M7 (Ret.)]

"... After reaching the second floor, wait for the guard to start walking away from you and grab the key that is laying on a bench halfway down the guard's patrol path. Turn around and open up the bedroom door. In the bedroom there is one door that leads to the balcony, and standing on the balcony you should be able to see a small ledge close to the wall. Jump on this ledge and keep walking until you reach a ladder, climb up on the roof and jump down on the balcony at the backside of the house. Open up the door with the key you've just picked up from the bench."

M7.