How sound is the statement that the Hadith narrated by Aisha from the Prophet, may Allah’s prayers and peace be upon him—which permits the uncovering of the face and hands—is weak, due to the revelation of the verse of Hijab after it, and because one of its narrators did not live at the same time as Aisha, and another is a liar?

If the intended narration is the Hadith of Asma, narrated by Abu Dawud and Al-Bayhaqi: "Indeed, when a woman reaches the age of menstruation, it is not proper that anything be seen of her except this and this..." then there is no liar in its chain of transmission, but its narrator from Aisha did not meet her. You can refer to Fatwas numbered (38567), (62048), (59394), and (32440) for more information on this Hadith and the issue of uncovering the face and hands.