No.
There were code changes in CPS13 that added tighter security to Windchill, and code was added in Navigate to work with those changes beginning with Navigate 8.5.8. Because of those changes, Navigate 8.5.8 and higher, including Navigate 9.1 that you ask about, are not supported with CPS12 or lower. If you were to try it you might find that some functionality works, but we have not QA'd that combination and do not guarantee that all functionality will work. If you filed a Tech Support case for an issue with an unsupported version mismatch, the response would be to upgrade to supported versions.
