Hello,
Could you please tell if the SRX is working in full packet based mode or selective packet bsed mode since you are using VPLS services on SRX which are available only in packet-mode (L2 mode).
Also i would like to inform here that VPLS is a L2 interface and COS features as per the documentation is not curretnly supported on L2 interfaces, hence it could be the reason for your rewrite rules not wokring on the VPLS interfaces.
Thanks,
Pulkit Bhandari
Please mark my response as Solution Accepted if it Helps, Kudos are Appreciated too. 