Some of the Powerline manufactueres specifically address the question of crossing the phases, e.g. TPLink
Q: Can TP-LINK powerline adapters work in different phases of three-phase circuit?
A: Yes, but its rate will be affected when crossing the phases. For three-phase four-line circuit, we suggest you use the topology below to get good performance.
There are specific products that are designed to connect to three-phase bus bars, e.g. devolo.