There was a group of arhats at the last part of the window.
All of arhats smiled slightly.
Why they displayed this group of arhats at last next to the group of arhats with despair and pain.
In my guess, the curators wanted to show the enlightenment could be attained after the process of the despair and the pain.
Arhats was not laughing loudly but smiled slightly.
In Korean saying, you don’t express your nice feelings loudly to preserve the pleasure as long as possible.
In my guess, the facial expressions of arhats seemed to tell they finally got arrived at the eternal peace and pleasure.
That must be the reason why they displayed those arhats at last.