we are running percona-xtradb-cluster-57, is it safe to revert the sql_mode to “sql_mode NO_ENGINE_SUBSTITUTION” as per percona-server-server-5.6 ?
It should safe to use “NO_ENGINE_SUBSTITUTION” , but also Percona XtraDB Cluster 5.7 comes with pxc_strict_mode which would not allow you to use any engine, but only InnoDB.