Include nested models but accessing to Proxy objects

Im working in Ember 3.1 and JSON:API format to get data from backend.

My models are something like follow:

// Continent model
export default DS.Model.extend({
  name: attr('string'),
  countries: hasMany('countries'),
});

// Country model
export default DS.Model.extend({
  name: attr('string'),
  president: belongsTo('president'),
  regions: hasMany('region')
});

// President model
export default DS.Model.extend({
  name: attr('string')
});

// Region model
export default DS.Model.extend({
  name: attr('string')
});

The way a fetch my models are:

fetchInformation: task(function* () {
    yield get(this, 'store')
      .findRecord('continent', continent,
        {
          include: 'countries,'
          + 'countries.president,'
          + 'countries.regions'
        }
      ).then((continent) => {
        get(continent, 'countries.firstObject') // This one gets resolved properly
        get(continent, 'countries.firstObject.president') // Get Proxy object
        get(continent, 'countries.firstObject.regions.firstObject') // Get Proxy object
      })

I thought that by using 'include' and the server replying as JSON:API specs, I would have access to all those properties.

To me it seems that those nested relationships needs to get resolved somehow.

What am I missing? Is there any way to work easily with nested models?