My read of the data table included in the linked article is that they have knocked the confidence in accelerating expansion down a couple orders of magnitude and thus brought the theory back on par with steady expansion. Text books, especially at the undegrad level currently take Dark Energy and accelerating expansion for granted, and also claim that all Type Ia supernovae are uniform. The uniformity of standard candles is what DE rests on. One of these can no longer be said to be uniform.

The fact that supernovae are not uniform is what will need to be revised in the textbooks.
God forbid people look closer at our assumptions on Cepheid Variable stars ;)