One line says:
Popularity may change at the beginning of a new season, but it will remain constant throughout that season.
But then a following line says:
Furthermore, the popularity of handicrafts may change each cycle according to both commercial trends in Limsa Lominsa and the type/amount of items you sell from your island.
It doesn't make sense to say that the popularity may change with a NEW SEASON and NOT change throughout the season, to then say that it changes depending on "trends" and what you are creating EACH CYCLE.

The first line seems misleading if you can in fact manipulate the popularity within each cycle and it is in fact not going to remain constant each season. They contradict each other.