FoundationDB does not support true geo-replicated multi-region distribution the way Cassandra, Spanner, Cockroach, etc do, at least not without paying huge latency/round trip costs. If you want to avoid that, the best you can have is a separate failover region, and, with FoundationDB 6, you can get closer-to-LAN latencies for failover deployments to separate regions (but only one region) while retaining ACID semantics. You could build truly global geo-distribution on top of it but that would have to be its own layer that implements 2PC/Paxos or something between regions. Ultimately you have to pay the toll somewhere in a truly consistent system like that if you want global availability (unless you're Spanner and have incredible hardware engineering that can be deployed across the globe).

Cassandra/Scylla are the only open source key value stores that do linear scalability by simply adding nodes even in huge, geo-distributed settings as far as I know, but they are ultimately AP systems. And Scylla just has absurd performance compared to Cassandra or FoundationDB. You just have to know what you're getting into. (But yes, ACID transactions are a good model for developers, and truly FDB's linearizable transactions and high scalability make it an obvious choice many CP systems, if you ask me.)