New Twiddle

components.my-component\.js

import Component from '@ember/component';
import { computed, set } from '@ember/object';

export default Component.extend({
  currentDateInternal: null,
  currentTimeInternal: null,

  init(...args) {
    this._super(...args)
    if (!this.currentTime) set(this, 'currentTime', moment().format('hh:mm:ss'))
    if (!this.currentDate) set(this, 'currentDate', moment().format('YYYY-MM-SS'))
  },

  currentDate: computed('currentDateInternal', {
    get(_key) {
      return this.currentDateInternal
    },
    set(_key, value) {
      set(this, 'currentDateInternal', value)
      return value
    },
  }),

  currentTime: computed('currentTimeInternal', {
    get(_key) {
      return this.currentTimeInternal
    },
    set(_key, value) {
      return set(this, 'currentTimeInternal', value)
    },
  }),
    
      actions: {
        changedatetime() {
          set(this, 'currentTime','x:x:x');
          set(this, 'currentDate', 'y-y-y');
        },
        submit() {
          const currentDate = this.currentDate;
          const currentTime = this.currentTime;
          this.callbackAction(currentDate, currentTime);
        },
      },
})

controllers.application\.js

import Controller from '@ember/controller';
import { set } from '@ember/object';

export default Controller.extend({
  currentDate: '1900-01-01',
  currentTime: '01-01-01',
  
  actions: {
    submitAction(date, time) {
      set(this, 'currentDate', date);
      set(this, 'currentTime', time);
    }
  }
})

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<br>
<br>
controller date time: {{currentDate}} {{currentTime}}
{{my-component currentDate=currentDate currentTime=currentTime callbackAction=(action "submitAction")}}
<br>
<br>

templates.components.my-component\.hbs

component date time: {{currentDate}} {{currentTime}}


<button onClick={{action "changedatetime"}}>change component datetime</button>
<button onClick={{action "submit"}}>submit</button>

twiddle\.json

{
  "version": "0.17.0",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.12.2",
    "ember-template-compiler": "3.12.2",
    "ember-testing": "3.12.2"
  },
  "addons": {
    "@glimmer/component": "1.0.0"
  }
}