Picture element card inside config-template-card seems to work fine but warning in console

Currently I have the following configuration: that seems to function properly:

type: custom:config-template-card
entities:
  - sensor.wirelesstag_east_intake_temperature
  - sensor.wirelesstag_main_office_temperature
  - sensor.wirelesstag_water_heater_room_temperature
  - sensor.wirelesstag_asic_room_temperature
  - sensor.wirelesstag_south_hot_temp_temperature
  - sensor.wirelesstag_main_building_front_door_sensor_temperature
  - sensor.wirelesstag_network_building_door_sensor_temperature
variables:
  setBadgeColor: |
    temp => {
      if (temp <= 35) {
          return 'blue';
      }
      else if (temp <= 90) {
        return 'green';
      }
      return 'red';
    }
card:
  type: picture-elements
  image: /local/images/river-road_floorplan.svg
  elements:
    - element: null
      type: state-badge
      entity: sensor.wirelesstag_east_intake_temperature
      style:
        '--label-badge-red': >-
          ${
          setBadgeColor(states['sensor.wirelesstag_east_intake_temperature'].state)
          }
        top: 41.5%
        left: 96.5%
    - element: null
      type: state-badge
      entity: sensor.wirelesstag_main_office_temperature
      style:
        '--label-badge-red': >-
          ${
          setBadgeColor(states['sensor.wirelesstag_main_office_temperature'].state)
          }
        top: 20%
        left: 87%
    - element: null
      type: state-badge
      entity: sensor.wirelesstag_water_heater_room_temperature
      style:
        '--label-badge-red': >-
          ${
          setBadgeColor(states['sensor.wirelesstag_water_heater_room_temperature'].state)
          }
        top: 14%
        left: 9.5%
    - element: null
      type: state-badge
      entity: sensor.wirelesstag_asic_room_temperature
      style:
        '--label-badge-red': >-
          ${
          setBadgeColor(states['sensor.wirelesstag_asic_room_temperature'].state)
          }
        top: 41.5%
        left: 20.5%
    - element: null
      type: state-badge
      entity: sensor.wirelesstag_south_hot_temp_temperature
      style:
        '--label-badge-red': >-
          ${
          setBadgeColor(states['sensor.wirelesstag_south_hot_temp_temperature'].state)
          }
        top: 33%
        left: 37.5%
    - element: null
      type: state-badge
      entity: sensor.wirelesstag_main_building_front_door_sensor_temperature
      style:
        '--label-badge-red': >-
          ${
          setBadgeColor(states['sensor.wirelesstag_main_building_front_door_sensor_temperature'].state)
          }
        top: 11%
        left: 41%
    - element: null
      type: state-badge
      entity: sensor.wirelesstag_network_building_door_sensor_temperature
      style:
        '--label-badge-red': >-
          ${
          setBadgeColor(states['sensor.wirelesstag_network_building_door_sensor_temperature'].state)
          }
        top: 91%
        left: 86.3%
  style: |
    :host {
      --primary-text-color: transparent;
      --label-badge-text-color: black;
      --label-badge-background-color: white;
    }

It seems that the config-template card recommends only applying the config-template card to individual elements inside the picture=element card like so:

type: picture-elements
image: http://hs.sbcounty.gov/CN/Photo%20Gallery/_t/Sample%20Picture%20-%20Koala_jpg.jpg?Mobile=0
elements:
  - type: 'custom:config-template-card'
    variables:
      - states['light.bed_light'].state
    entities:
      - light.bed_light
      - sensor.light_icon_color
    element:
      type: icon
      icon: "${vars[0] === 'on' ? 'mdi:home' : 'mdi:circle'}"
      style:
        '--paper-item-icon-color': '${ states[''sensor.light_icon_color''].state }'
    style:
      top: 47%
      left: 75%

It seemed to me that would have created much more code than was necessary and I wanted all the picture elements to be able to use the same function that I defined once in the config -template-card variables.

Can anyone enlighten me as to why the way I am doing it is not recommended? Or what problems I might run into that I may be unaware of doing it like this.

Thank you for any help in advance!