You... got the culprit but changed the howdunnit which was already right??? I am confused????
In all seriousness though, well done!
Gohda was planning to murder Eva. In order to do so, he poisoned her meal. Eva and Krauss swapped meals at the dinner table. After lunch, Eva took Krauss aside and agreed to have a chat about the inheritance in private, which is why Eva left Hideyoshi behind after lunch concluded.
During break, Eva took Krauss to her room and held a discussion with him. However, she needed the bathroom and left the room, locking it behind her. Krauss added the chain for extra security, in order to satisfy Eva's fear that she'd be seen speaking on good terms with Krauss.
Whenever Eva returned from the bathroom however, there was no response from the door. Krauss had died from poisoning inside the room. This is when she went to find Genji.
Well played, everyone.