Custom class and custom label for Entry Detail Save button

gfroms-examples.php

function modifygform_entrydetail_update_button() {
	$mode = empty( $_POST['screen_mode'] ) ? 'view' : $_POST['screen_mode'];

	$button_text      = $mode == 'view' ? __( 'Update Entry', 'gravityforms' ) : __( 'Update Entry', 'gravityforms' );
	$disabled         = $mode == 'view' ? '' : ' disabled="disabled" ';
	$update_button_id = $mode == 'view' ? 'gform_edit_button' : 'gform_update_button';
	$button_click     = $mode == 'view' ? "jQuery('#screen_mode').val('edit');" : "jQuery('#action').val('update'); jQuery('#screen_mode').val('view');";
	$update_button    = '<input id="' . $update_button_id . '" ' . $disabled . ' class="button button-large button-primary my-custom-button-class" type="submit" tabindex="4" value="' . esc_attr( $button_text ) . '" name="save" onclick="' . $button_click . '"/>';
	return $update_button;

}
add_action('gform_entrydetail_update_button', 'modifygform_entrydetail_update_button');