Using the show warnings command, you can check the warnings (up to the last five) issued to the agent log (mcmd.log). For example:

mcm> set delayed_insert_timeout:mysqld=400 mycluster;
+-----------------------------------+
| Command result                    |
+-----------------------------------+
| Cluster reconfigured successfully |
+-----------------------------------+

mcm> show warnings;
+---------+------+-------------------------------------------------------------------------------------------------------+
| Level   | Code | Message                                                                                               |
+---------+------+-------------------------------------------------------------------------------------------------------+
| Warning | 0    | 2021-07-12 21:27:38 Config variable delayed_insert_timeout was deprecated in mysqld 5.6.7             |
| Warning | 1287 | 2021-07-12 21:27:38 '@@delayed_insert_timeout' is deprecated and will be removed in a future release. |
| Warning | 1287 | 2021-07-12 21:27:38 '@@delayed_insert_timeout' is deprecated and will be removed in a future release. |
+---------+------+-------------------------------------------------------------------------------------------------------+
3 rows in set (0.10 sec)