ExtJs - How to fetch elements from childEls

ExtJs - How to fetch elements from childEls

I'm using the snippet bellow to add some HTML elements to the top of a
FormPanel:
{
xtype: 'component',
itemId: 'form-top',
cls: 'form-top-items',
renderTpl: [
'<div id="{id}-formHelp" class="form-help">',
'<span class="form-help-text">{helpText}</span>',
'</div>'
],
renderData: {
helpText: __("Os campos com * são de preenchimento obrigatório.")
},
childEls: [
{name: 'formHelp', itemId: 'centris-form-help'}
]
}
But once the component is rendered, I can't fetch any child items.
I'm expecting a way to access the formHelp item somehow, but can't find it
anyway bellow the form-top component.