The mental model is slightly different. FDWS are basically server -> server linkages, not literally clustering. As a result, data consistency between servers

The mental model is slightly different. FDWS are basically server -> server linkages, not literally clustering. As a result, data consistency between servers is less of an issue - the data is likely to only live in one place (read replicas and failovers notwithstanding). There may be some error handling and try/rollback around remote transactions baked into postgres_fdw but I'm not familiar enough to say.