refineCollectionShardKey should create the same chunk and tag boundaries for the refined shard key as a collection being sharded on the same shard key. There are tests in refine_collection_shard_key_basic.js that verify this behavior. However, these tests fail in a few passthrough suites including, but not limited to,

• embedded_router_jscore_passthrough
• sharding_jscore_passthrough_with_auto_bootstrap
• causally_consistent_jscore_passthrough

For logs, please see this patch to turn the tests from refine_collection_shard_key_basic.js into core_sharding tests. Are these failures expected behavior in testing?