As far as the plan builder goes, its worth lnowing how A, B, and C events are treated. It’s not neccessarily how important they are to you, but more what type of fitness they require and what theu take out of you. The plan builder obviously makes sure your plan targets your last A race, so fits it into the available time until that. Apart from that, it will give you a taper week before and a recovery week after an A race, but for a B race it will only give you the day before, no long taper. There is nothing stopping you from dropping a few more workouts for extra taper, or after for recovery, even if you’ve called it a B race.
With that in mind, I’d probably call the first race your A race, and afterwards make your own plan. Maybe an ultra-condensed base-build-spec cycle of four weeks. Have a bit of recovery after the race (or not, depends what it took out of you), then spend a week getting some aerobic endurance in, then two weeks of ‘build’ sessions, before another taper and the next race.
What I’ve learned from my cx season is that it’s not a good idea to try to do the speciality plan during the season, it just doesn’t work and you’re missing out on some session that were thefe for a reason.