Some direction on adding or suppressing liturgical feasts:
60. As regards the liturgical year, each particular church and religious family adds its own celebrations to those of the universal church, after approval by the Apostolic See. (Cf. Normae Universales de Anno Liturgico et de Calendario, 49, 55; Congregation for Divine Worship, instruction Calendaria Particularia, 349-370.) Episcopal conferences can also, with the prior approval of the Apostolic See, suppress the obligation of certain feasts or transfer them to a Sunday. (Cf. Canon 1246.2.) They also decide the time and manner of celebrating rogationtide and ember days. (Cf. Normae Universales de Anno Liturgico et de Calendario, 46.)
With Christian countries abandoning the obligatory nature of some observances and moving others to Sunday, I can’t suppose very many obligatory days are successful in mission countries. Any readers know of any in which some tradition has developed?