Troparia, kontakia, akathists and canons have for centuries been composed in good faith, and in anticipation of pending glorification, before a person has been "officially" glorified, including at local level (e.g. by the Greek church, the Russian church, etc). The point which needs to be stressed is that, even if that person is, with time, formally declared a saint, such pre-glorification hymnody must be used only for private devotional use. Any such hymnody must be assessed by the Church hierarchy as theologically and doctrinally sound before it is approved for public, liturgical use. IIRC, all local churches have a body or committee of some sort, made up of clerics and hymnographers, which examines such texts.
Just to add another really "techy" thing, in the church of Greece there are only 5 official hymnogrophers whose job it is to compose new hymns for the church. they are in charge of any new hymns that enter into the menaion, or any other book or service.
Just adding a nuance.