There is an email address for reporting bugs with HLSIM.
Before reporting a problem, please try to narrow it down to a small, complete and repeatable example. Make your problem description as precise as you can. That way we have a chance or reproducing the problem, which we probably need to do in order to understand the problem, which we need to to in order to fix it.
The email address is: bug-hlsim@martigny.ai.mit.edu