Is what is stated in the circulating message regarding a Mauritanian scholar's ablution, where he performs "madmadah" (rinsing the mouth) and "istinnshaq" (sniffing water into the nose) after completing the ablution, and repeats washing the hands along with the forearms, correct, and is it considered among the Sunnahs that must be revived?

Rinsing the mouth (madmada) and sniffing water into the nose (istinshaq) are Sunnah in ablution according to the majority of scholars. Therefore, whoever omits them, their ablution is valid, and they are not required to perform them after ablution. The Malikis, however, deem it recommended to perform them after ablution for someone who forgot them. As for washing the hands up to the elbows, the palms must be washed along with them. It is not sufficient to wash them only at the beginning of ablution, because washing them at the beginning of ablution is a Sunnah, whereas washing them along with the hands up to the elbows is obligatory.