To get coverage of read your own writes behavior for local operations on a single node without causal consistency without failovers, there should be transaction passthrough suites that use transactions with "local" read concern and commit with w:1 write concern in non-causally consistent sessions. Non transaction operations should also use these read and write concerns.
This can be done by changing the existing concurrency_sharded_replication_majority_multi_stmt_txn(_with_balancer) suites to use "local" read concern instead of "majority." These suites already commit with w:1 write concern.
The existing multi_shard_majority_multi_stmt_txn suite should also be changed to use "local" read concern and its commit write concern should be changed from w:majority to w:1.