I hadn't heard of Chirattakonam before, but there's a Vatican-sponsored exhibit of church-recognized miracles that tours, and it's included there. So it would naturally follow, on the basis of its inclusion, that it's officially approved as one of the principal Eucharistic miracles:
http://www.therealpresence.org/eucha...r/engl_mir.htm
http://www.therealpresence.org/eucha...rattakonam.pdf
As far as actual commentary goes, the best I can find is this article:
http://www.freerepublic.com/focus/f-...n/988409/posts
which includes the testimony of Fr. Johnson Karoor, the parish priest, and the commentary of his superior, Archbishop Cyril Mar Baselios. I think it's important to note that the archbishop's commentary is in the present tense, which makes it sound like he's standing right there, and addressing fellow onlookers during the course of the miracle. Having the support and recognition from the local archbishop would definitely be an important component... I don't know about Eucharistic miracles specifically, but as far as apparitions go, I believe that the Vatican itself rarely comments on the validity of an apparition, but they leave that in the hands of the local diocese. So that might account for why you're having trouble finding something that explicity states Vatican-approval, since it may be left to the local bishops to determine whether or not something is worthy of belief. (Constat de supernaturalitate.)