core/homeassistant/components/cast/strings.json

{
  "config": {
    "step": {
      "confirm": {
        "description": "[%key:common::config_flow::description::confirm_setup%]"
      }
    },
    "abort": {
      "single_instance_allowed": "[%key:common::config_flow::abort::single_instance_allowed%]",
      "no_devices_found": "[%key:common::config_flow::abort::no_devices_found%]"
    }
  }
}