Are the devotees that study/chant the Chandi known as Srividya Upasakas?
Maybe yes maybe no. Certainly if they want that title, they are entitled to use it, because they are performing their disciplines using the knowledge of the highest respect. But Srividya generally applies to a specific branch of knowledge which includes worship with the 15 or 16 syllable mantras. Therefore, it is a very subjective issue.