Could anyone please help me with API that i can use to check whether the server is reporting to TEM or not.
There are at least two ways to go about this. You can leverage the Client Compliance API, and the last report time of <client> inspector, or query the BigFix Server itself via the REST API, and some session relevance such as the following:
last report times of bes computers whose (name of it as lowercase = "Server1" as lowercase)
or if you want a simple boolean True/False, maybe something like the following:
(last report time of it > (now - 1 * hour)) of bes computers whose (name of it as lowercase = "Server1" as lowercase)