I'm not able to open the links to the DLI archives for the book by Ramadas Gaur and the article by DC Sircar (the gateway connection always times out).
It seems to me that a passing mention to a Narasimha Sampradaya could actually be a reference to the Datta Sampradaya in Maharashtra and Karnataka, where the name of a 14th-15th century guru named Narasimha Sarasvati of Ganagapura stands tall.
The Srigurucaritra of Gangadhara Sarasvati, written originally in Marathi, and translated to Sanskrit in the late 19th century, is an account of his life, which is often recited by adherents of the Datta sampradaya.
Best regards,
Vidyasankar