Yes, it’s a limitation of Android, which only provides one set of SyncColumns per event or per contact: this only supports one sync adapter per contacts list or per calendar.
However at the server side there is no such limitation. Any authorised program can connect to the CardDAV or CalDAV server. So if your server is on your PC and you can find a PC program (or write one) which synchronises between the CardDAV server and your Google contacts list or between the CalDAV server and your Google calendar, you can get those synced up with your Android device.
It looks as if Google’s calendar and contacts will now act as CalDAV and CardDAV servers, so an alternative option might be to use those as your server instead of your own PC if you were using that. If you have a PC application that also talks to your server, it should be able to talk to Google’s one as well.