After going through a bit of a rabbit hole then experiencing Occam’s razor and spending admitedly too much time to find it; to lose focus on a component whether that’s through pressing the enter key, message handlers, or any other scripted action… use the .focus() method on the root container component 
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Although your component path may be different the following worked for me to force blur on a text field when pressing the enter key.
if event.key == 'Enter':
self.view.getChild("root").focus()
As a little (expected) bonus, and something to remember, this triggers the onBlur focus event of the component.
Good luck!