Is Yaw Yan ardigma a good system to crosstrain with Silat Cimande? I'm going to give it a try anyway just to see.
Therefore why are you asking? Personally I'd say a more orthodox system of Kali would be a better fit, but at the end of the day what are you looking to gain from cross training?
This a bit biased because I think YawYan is a great fma. Time spent learning Yawyan will never be a waste of time.
I really like their kicks, but I prefer the Lacoste hands. Going back to the OP though, as he's doing Cimande which is a hand heavy system maybe it WOULD be a good fit.