Ayuda, por favor

The Mass that I have attended for the past two Sundays (Novus Ordo mostly in latin) is in a chapel that has missalettes with Spanish and English readings. (The chapel also has Adoremus Hymnals) In scanning the misselette I noticed the phrase "en aquel tiempo" comes up frequently in the readings for several Sundays. I know this is some kind of an idiom and that it means something like "at the time" but can anyone tell me why it is in so many of the readings? How come the phrase is not in the english or am I totally misreading the spanish?