17. As for the use of “artificial” languages, proposed from time to time, the approval of texts as well as the granting of permission for their use in liturgical celebrations is strictly reserved to the Holy See. This faculty will be granted only for particular circumstances and for the pastoral good of the faithful, after consultation with the Bishops principally involved.[Cf., for example, Congr. for Divine Worship and the Discipline of the Sacraments, Normae de celebranda Missa in «esperanto», 20 March 1990: Notitiae 26 (1990) 693-694.]
The only problem I see with this paragraph would be handling modern manufactured languages like what the deaf and hearing impaired use in various countries.