I noticed some bugs while using Systemic 2.16. Please find the list below.
Please correct me if I'm wrong but I think relativistic effects are not included in the code. The relativistic precession of pericenter may be important for hot planets. For instance, in the case of WASP-12 the expected period of the precession is about 17 yr, and observations obtained so far cover its significant fraction.
Thanks for the report, the latter all look like easily fixable bugs for the next point release (in a couple of weeks at most).
Relativistic effects are not included but would not be hard to implement. I'll have a look at the literature and get back to you.