What is the ruling on an Imam's oversight regarding the second prostration in the last rak'ah of the Asr prayer?

Prostration (sujud) is one of the pillars of prayer. If someone forgets it, they must perform it immediately, then perform the prostrations of forgetfulness (sujud al-sahw), unless a long time has passed after finishing the prayer, in which case they must repeat the prayer. Ibn Qudamah said: "Whoever omits a pillar forgetfully and then remembers it during the prayer, he should perform it. If he does not remember it until after finishing the prayer, then if a long time has passed, he must repeat the prayer. If not much time has passed, he should build upon it [by performing the omitted pillar] and then perform the two prostrations of forgetfulness. The determination of 'long time' and 'short time' refers to custom and common practice."