The guild leaderboards in challenges show the most up-to-date score for the guild - the score from the most recent challenge.
If a challenge is currently underway, the stars gained in the current challenge will be the guild's score. If a challenge is not currently underway, the stars gained in the previous challenge will be the final score for the guild.
If a challenge is currently underway, the stars gained in the current challenge will be the guild's score. If a challenge is not currently underway, the stars gained in the previous challenge will be the final score for the guild.