There are many ABNT styles in the CSL github repository, but none renders anon articles correctly.
In the bibliography it is supposed to have the first word of the title uppercased, if there is an article word (a, an, the), that is also included in the uppercasing. When citing it, only the first word should be shown and the rest replaced by “…”, as shown bellow:
(A MAMMOTH…, 2004, p. 21–24)
A MAMMOTH guilt trip: Criminalising the American company. The Economist, p. 21–24, 2004.
(A FLOR…, 1995, p. 4)
A FLOR Prometida. Folha de S. Paulo, São Paulo, p. 4, 21 abr. 1995.
(NOS CANAVIAIS…, 1995, p. 2)
NOS CANAVIAIS, mutilação em vez de lazer e escola. O Globo, Rio de Janeiro, 16 Jul. 1995. O País,
I looked into CSL documentation but I could not find a way to do this styling, it doesn’t seem to be currently possible.