HAZILAM At the top of the Zentralbahn webpage you got your screenshot from, there’s a statement in brackets saying that the right side is the bottom half of the displayed seats.
Note that your screenshot includes another “info” statement with the double arrow saying that the direction of travel may change during the journey… it definitely WILL change in Meiringen (but Lake Brienz will still be on the right side afterwards). Zoom up Meiringen station on some online map such as Google, and you’ll understand.
