CAN Bus Physical Layer Twisted pair or not
Yes, use twisted pair.  Failing to do so for a differential signal is self-defeating.  Don't forget to include 120-ohm termination resistors at each end of the transmission line.

The less connectors in any transmission system the better.  Connectors are almost guaranteed to present an impedance discontinuity, and hence will cause reflections.

Transmission line stubs of any length are also a source of reflections and (if I'm reading your description correctly) you have transmission line stubs of several metres.  The longer the stub, the worse the impact of the reflections.

Reflections are bad because they can cause destructive interference, i.e. they can corrupt any transmitted data.

I'd use a longer primary (twisted pair) cable, less connectors and shorter stubs.  Run the primary cable as close to each node as you can, even if it means that the cable has to be longer.