Can I get a CSE in Heritage Institute of Technology with 3,870 rank in WBJEE? I got ECE there in round 1, should I risk it and go for round 2?

With a rank of 3870, your prospects of receiving CSE at Heritage are very good. According to the 2021 cutoff trends, the required cutoff for the branch was 3214. 

If you have got ECE in the first round of counseling there is no risk entering into the 2nd round as you will not lose your allocated seat. Additionally, you cannot lock your seat in the first round. This option is available only after the second round of counseling. 

The bottom line is that once you've been allocated a college and a major, it can’t be taken away. It will only be upgraded if someone above you does not enroll in the college or the course to which they have been assigned. CSE is available and is simple to obtain. Also, I believe there is no risk factor; therefore, you may keep your seat and proceed to the second round of counseling.