Problems with Templates, Volume Control as a Light, and Homekit

I've been trying to add voice control of my AVR via Home Assistant and Homekit, but I'm having difficulty setting this up. First off, before anyone says: "using a light for voice control? WTF?" Please refer to this link:

https://community.home-assistant.io/t/template-light-as-speaker-volume-control/80742

Homekit apparently has no mechanism in controlling volume. (At least so it seems, the article above may be old? But I haven't seen anything contrary to this? I digress). Regardless, I've implemented the yaml example contained in the above link, but for clarity sake, here's mine:

- platform: template
  lights:
    media_zone:
      friendly_name: "Media Zone"
      value_template: "{{ is_state('media_player.denon_avr_s730h', 'on') }}"
      turn_on:
        service: media_player.turn_on
        data:
          entity_id: media_player.denon_avr_s730h
      turn_off:
        service: media_player.turn_off
        data:
          entity_id: media_player.denon_avr_s730h
      set_level:
        service: media_player.volume_set
        data_template:
          entity_id: media_player.denon_avr_s730h
          volume_level: "{{ (brightness | float / 255 ) }}"
      level_template: "{{ (state_attr('media_player.denon_avr_s730h', 'volume_level')|float * 255)|int }}"

In Homekit, this kind of works, what's weird is in how it works. For some reason, even whole base ten #s work, but odd base ten #s do not. Additionally, nothing in between works. In other words:

"Hey Siri, set the Media Zone volume to 40%" This works 20%, 40%, 60%, 80% all work

But, 10%, 30%, 50%.... and 23%, 44%, 32%, etc. do not.

Any help? I've tried tweaking the templates but I still get the same results as above. Or, is there a better way?