They're based on Raft--that's not a consensus protocol that's designed for multi-datacenter operations. I suspect you'll have reliability and throughput issues fairly quickly, just as you see with multi-datacenter zookeeper.

The solution Google uses for this kind of problem: multidatacenter transactions are rare, so they're not optimized for latency (instead for reliability), and they tend to use 2PC, as it's easier to get right with unpredictable WAN latencies.