While reading the code in this area this morning, I noticed that wal_log_hints and track_commit_timestamp are not mentioned in the desc routine of XLOG_CHANGE_PARAMETER. Also, it is not mentioned in postgresql.conf.sample that a value update of wal_log_hints requires a system restart.
In order to fix those things, attached are two patches: - patch 1 should be applied back to 9.4 where wal_log_hints has been added
You got the wal_level and wal_log_hints strings backwards: