There are several differences between this fragment and the Leiden manuscript and first edition of the Yerushalmi. Some of the fragment readings have been suggested by mefarashim. If you are familiar with this sugya, you will know that there is a (partial) parallel in Hagiga and that in the previously known text of this Yerushalmi, the words hacha and hatham are used as if the sugya was the one in Hagiga - in other words, the sugya in our printed texts and manuscript calls Mishna Hagiga 'here' instead of 'there.' The lashon of the fragment is also interesting, as it spells 'v'at' (vav aleph tav in our editions) without an aleph.It also has 'Rabbi Yudan' where our text has "Rabbi Yehuda.' My guess as to the reference of the 'new sentence' is a place where our text is indeed unintelligible to the point that the mefarashim did all amend it, and they did not get it the way it is in the fragment.The text we had, translated literally, said, "It only applies that it is not or in what is bought with maaser money which became impure." The text in the fragment, which unfortunately is cut off at the beginning of every line, says, "It only applies if it had been bought with maaser money, or ... became impure."
By the way, what they are talking about is the proper okimta for a statement that maaser sheni oil which becomes impure cannot be used even in a lamp (like impure terumah oil).
I do think the wording of the press release was a little overblown.
Sorry about your limited diet in the spring.