Read Only set nested

controllers.application.js

import Ember from 'ember';
import {computed} from '@ember/object'
import {isNone, isPresent} from '@ember/utils'

export function aliasFallbacks (...fallbacks) {
  return computed(...fallbacks, function () {
    for (let i = 0; i < fallbacks.length; i++) {
      const fallback = fallbacks[i]

      const result = this.get(fallback)
      if (isPresent(result)) return result
    }
  }).readOnly()
}
export default Ember.Controller.extend({
  backupApp: {
   name: 'Foo'
  },
  app: undefined,
  aliasApp: aliasFallbacks('app', 'backupApp'),
  actions: {
   toggleAppName () {
     // this.set('aliasApp', 'Bar') // Throws error
     
     this.set('aliasApp.name', 'Bar') // Doesn't. can I mark a whole object as read only?
   }
  }
});

templates.application.hbs

<h1>Welcome to {{aliasApp.name}}</h1>
<br>
<br>
{{outlet}}
<button {{action "toggleAppName"}}> Change </button>
<br>
<br>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}