In my Father McGuire's New Baltimore Catechism No. 1,
The term non catholic christian is not recognized. And
in article 91, page 59 that a Catholic sins against the
faith by not believing what God revealed, and taking
part in non-Catholic worship.
In the Complete Catechism of the Catholic Religion,
by Joseph Deharbe S.J. on pages 148-149, in summary,
the term heretics, schismatics are used.
Article 69 points out that those that are heretics, and
schismatic without their own fault, and sincerely searches
for the truth, and in the meantime do the will of God to
the best of their knowledge, although they are
separated from the church, remain, however, united to
the soul of the church, and partakes of her graces.
The term non catholic christian is uniquely vatican 2.