Nope. Church councils are only considered infallible on "matters of faith and morals". The language to be used in Church is neither--it's more like "company policy".
This is false. Church councils are not considered infallible unless they state something infallibly with regard to faith and morals, binding all of the faithful to it, which a statement containing an anathema certainly does.
It has been sometimes said that it is impossible to know whether or not a theological definition has been issued; but very few words are needed to show that the assertion is without foundation. At times, doubt will remain about the definitive nature of a decree, but as a rule no possibility of doubt is consistent with the terminology of a definitive decree. Thus in the doctrinal teaching of a general council, anathema attached to condemned errors is a certain sign of an infallible definition. Words also like those in which Pius IX solemnly defined the doctrine of the Immaculate Conception of the Blessed Virgin give irrefutable proof of the definitive nature of the decree: "By the authority of Our Lord Jesus Christ and of the Blessed Apostles Peter and Paul, and by Our own authority, We declare, pronounce and define the doctrine . . . to be revealed by God and as such to be firmly and immutably held by all the faithful." No set form of words is necessary; any form which clearly indicates that the four requisite conditions are present suffices to show that the decree is a definition in the strict sense.