Make difference between selecting existing and creating a new entity as clear as possible

This change works —but overwrote my changes via hook_inline_entity_form_reference_form_alter

I think what is happening:

class InlineEntityFormComplexOpen
  public function formElement
    $element['form'] += inline_entity_form_reference_form($element['form'], $form_state);
  

which calls

  \Drupal::moduleHandler()->alter('inline_entity_form_reference_form', $reference_form, $form_state);

... and then after the alter this #value is set where it can't be changed...

$element['form']['actions']['ief_reference_save']['#value'] = ...

I'm not sure the best way to keep the code concise — maybe use hook_inline_entity_form_reference_form for the potential-conflict variables?