I ran quickly my check on the S7… these are all the commands I can see.
My first guess to try is the get_water_box_custom_mode
"model": "roborock.vacuum.a15",
"commands": [
"set_clean_motor_mode",
"set_camera_status",
"set_ignore_carpet_zone",
"set_clean_sequence",
"set_homesec_password",
"set_child_lock_status",
"set_carpet_clean_mode",
"set_ignore_identify_area",
"set_dust_collection_switch_status",
"set_map_beautification_status",
"set_fan_motor_work_timeout",
"set_mop_motor_status",
"set_collision_avoid_status",
"set_flow_led_status",
"set_dust_collection_mode",
"set_custom_mode",
"set_water_box_custom_mode",
"set_timer",
"set_dnd_timer",
"set_timezone",
"set_app_timezone",
"set_carpet_mode",
"set_lab_status",
"set_server_timer",
"set_fds_endpoint",
"set_led_status",
"set_customize_clean_mode",
"set_mop_mode",
"set_airdry_hours",
"set_timer_dup",
"set_map_name",
"set_multi_map_timer_different_map_tip",
"set_multi_map_timer_switch_different_map_tip",
"set_multi_map_timer_different_map_save_tip",
"get_clean_motor_mode",
"get_camera_status",
"get_timer_summary",
"get_timer_detail",
"get_testid",
"get_clean_sequence",
"get_turn_server",
"get_device_sdp",
"get_device_ice",
"get_homesec_connect_status",
"get_child_lock_status",
"get_carpet_clean_mode",
"get_random_pkey",
"get_multi_maps_list",
"get_dust_collection_switch_status",
"get_map_beautification_status",
"get_fan_motor_work_timeout",
"set_server_timer",
"set_fds_endpoint",
"set_led_status",
"set_customize_clean_mode",
"set_mop_mode",
"set_airdry_hours",
"set_timer_dup",
"set_map_name",
"set_multi_map_timer_different_map_tip",
"set_multi_map_timer_switch_different_map_tip",
"set_multi_map_timer_different_map_save_tip",
"get_clean_motor_mode",
"get_camera_status",
"get_timer_summary",
"get_timer_detail",
"get_testid",
"get_clean_sequence",
"get_turn_server",
"get_device_sdp",
"get_device_ice",
"get_homesec_connect_status",
"get_child_lock_status",
"get_carpet_clean_mode",
"get_random_pkey",
"get_multi_maps_list",
"get_dust_collection_switch_status",
"get_map_beautification_status",
"get_fan_motor_work_timeout",
"get_mop_motor_status",
"get_collision_avoid_status",
"get_flow_led_status",
"get_dust_collection_mode",
"get_photo",
"get_multi_map",
"get_prop",
"get_status",
"get_map",
"get_map_v1",
"get_map_v2",
"get_custom_mode",
"get_water_box_custom_mode",
"get_clean_summary",
"get_clean_record",
"get_clean_record_map",
"get_clean_record_map_v2",
"get_consumable",
"get_timer",
"get_dnd_timer",
"get_serial_number",
"get_log_upload_status",
"get_sound_progress",
"get_current_sound",
"get_timezone",
"get_carpet_mode",
"get_sound_volume",
"get_fw_features",
"get_fresh_map",
"get_persist_map",
"get_collision_avoid_status",
"get_flow_led_status",
"get_dust_collection_mode",
"get_photo",
"get_multi_map",
"get_prop",
"get_status",
"get_map",
"get_map_v1",
"get_map_v2",
"get_custom_mode",
"get_water_box_custom_mode",
"get_clean_summary",
"get_clean_record",
"get_clean_record_map",
"get_clean_record_map_v2",
"get_consumable",
"get_timer",
"get_dnd_timer",
"get_serial_number",
"get_log_upload_status",
"get_sound_progress",
"get_current_sound",
"get_timezone",
"get_carpet_mode",
"get_sound_volume",
"get_fw_features",
"get_fresh_map",
"get_persist_map",
"get_room_mapping",
"get_recover_maps",
"get_recover_map",
"get_map_status",
"get_segment_status",
"get_server_timer",
"get_network_info",
"get_led_status",
"get_customize_clean_mode"
]
},