From what i understand she said "(ko)mori no kuma-san" as to turn the song into her name,
but the song "mori no kuma-san" is about a bear in the forest right? so she was wearing bear panties?
if so, then the joke was translated in quite a weird manner... not like i'd do better
(something like "the bear in komori's" while at the same time "the bear in the forest"... sounds difficult.)
also my knowledge in japanese is VERY limited so i might be wrong there
Edit: but i DO understand that they used the official(?) translation to the song. i just think it's weird as it lost some context (like a bear never being mentioned)