Q. Is it correct that Dasam Granth was first introduced in literature by Malcolm in 1810 AD in his book titled “Sketch of the Sikhs”?

As per the answer above it is quite clear that nobody apart from Guru Gobind Singh introduced the Granth into Khalsa psyche in the 17th century. Sri Gur Sobha Granth written in 1711 by Guru Sahib’s poet Senapati was one of the first books to illuminate the writings in the Sri Dasam Granth. This book is written not only in the style and language of the Sri Dasam Granth but some verses are similar to the verses found in Sri Bachitra Natak, most notably the battles of Guru Gobind Singh Ji. It is clear that the court poets wanted to emulate the writings of Guru Gobind Singh Ji as these were read in the Guru’s Durbars. John Malcolm wrote his book “Sketch of the Sikhs” over 100 years after Kavi Senapati, so he could not have introduced Sri Dasam Granth in literature. However Malcolm, a noted historian and statesman, who not only wrote extensively on the life in India, but also Iran, narrated what he saw in Amritsar, that the Akali Singhs revered two Granths, “Adi Granth” and “Dasven Patshah Ka Granth”. He wrote a detailed description of how Akali Singhs who were in-charge of Akal Takht pass Gurmatta in a
congregation. There he saw both the Granths being read and revered.