Major It has been reported that when a Cluster object is created with buckets configurations defined for for buckets that exist on different clusters, query requests may get routed to the wrong cluster - this needs to be investigated further.
final stages of review...
The issue is related to Uri caching - specifically the Uri cache is overwritten by the most recent config change that has occurred. A possible fix is either to use hash-table to store the uri's where the key is bucketConfig or something uniquely identifying the configuration or by making the Uri cache instance an variable and passing the CouchbaseConfigContext down to each layer that needs to use it.
https://github.com/couchbase/couchbase-net-client/blob/master/Src/Couchbase/Configuration/CouchbaseConfigContext.cs#L258-L260