Again, review your conjunctions. It is evident you do not understand the application of "and" and "or."
Sarufi is not a loanword. The usage of a foreign word denotes its application in the context of the source language. Grammar is the body of syntax and rules applicable to the English language, whereas Sarufi is the body of syntax and rules applicable to Swahili.
Sarufi and grammar are not used interchangeably because they represent 2 distinct languages!