I was able to follow all the stories up to two episodes before the most recent one.
この場合、次のような言い方ができますよ。
ーI was able to follow all the stories up to two episodes before the most recent one.
「最新話の2話前までは話についていけた」
to follow で「ついていく」
up to two episodes before the most recent one で「最新話の2エピソード前まで」
ご参考まで!