Are the calculations derived from the noble Prophetic حديث regarding the age of the Islamic Ummah, which predict its end at a maximum of 1500 years, correct in their context? And if so, why did not the prominent scholars of Islam take notice of them?

The aforementioned Hadith is authentic, but what is meant by it is the abundance or scarcity of deeds, not the length of time. The period between Jesus and our Prophet Muhammad, peace and blessings be upon him, is longer than the period between our Prophet and the Hour. The time of the cold wind and all the major signs of the Hour are drawing near, but no one knows precisely when that will be, and the knowledge of the Hour is with Allah Almighty. The calculations mentioned are incorrect and should not be relied upon.