Good point, I'd gotten used to that and forgotten how it is kind of counterintuitive at first. Our base test helper object does this:

  get root() {
    // It is important here to run cy.get() 
    // each time this property is accessed. 
    // Lots of methods of this class chain 
    // off of `this.root` so it needs to be 
    // re-evaluated every time.

    return cy.get(rootComponentCss);
  }

  find(selector: string, options?: any) {
    return this.root.find(selector, options);
  }

...so that component-specific test helper objects (subclasses) can just do something like:

  get sendMissileAlertButton() {
    this.root.find('.x-hawaii-missile-incoming');
  }

That way, it looks up the target element every time it is used in a test.

And in tests, you can just do:

    tester.root.find('select.foo').select('hoge');
    tester.sendMissileAlertButton.click();

EDIT: fixed code example, sorry! ;-)