diff --git a/core/lib/Drupal/Core/Entity/ContentEntityForm.php b/core/lib/Drupal/Core/Entity/ContentEntityForm.php
index c0882a2..3740600 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityForm.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityForm.php
@@ -50,10 +50,10 @@ public static function create(ContainerInterface $container) {
    */
   public function form(array $form, FormStateInterface $form_state) {
     $form = parent::form($form, $form_state);
-
-    // Content entity forms only need to rebuild the entity in the validation
-    // and the submit handler because Field API uses its own #after_build
-    // callback for its widgets.
+    // Content entity forms do not use the parent's #after_build callback
+    // because they only need to rebuild the entity in the validation and the
+    // submit handler because Field API uses its own #after_build callback for
+    // its widgets.
     unset($form['#after_build']);
 
     $this->getFormDisplay($form_state)->buildForm($this->entity, $form, $form_state);
diff --git a/core/lib/Drupal/Core/Entity/EntityForm.php b/core/lib/Drupal/Core/Entity/EntityForm.php
index d5b2c7a..fb015c7 100644
--- a/core/lib/Drupal/Core/Entity/EntityForm.php
+++ b/core/lib/Drupal/Core/Entity/EntityForm.php
@@ -158,12 +158,13 @@ public function processForm($element, FormStateInterface $form_state, $form) {
   /**
    * Form element #after_build callback: Updates the entity with submitted data.
    *
-   * This is the entity object builder function that allows rebuilt forms (e.g.
-   * submitted via AJAX) to keep relying on entity values instead of form state.
+   * Updates the internal $this->entity object with submitted values when the
+   * form is being rebuilt (e.g. submitted via AJAX), so that subsequent
+   * processing (e.g. AJAX callbacks) can rely on it.
    */
   public function afterBuild(array $element, FormStateInterface $form_state) {
-    // If the form is processing user input, rebuild the entity with the current
-    // form values.
+    // Rebuild the entity if #after_build is being called as part of a form
+    // rebuild, i.e. if we are processing input.
     if ($form_state->isProcessingInput()) {
       $this->entity = $this->buildEntity($element, $form_state);
     }