Improve i18n negligence in MultiSelectionInspector (#12054)

Addresses an issue introduced in #12050.

packages/editor/src/components/multi-selection-inspector/index.js

@@ -1,7 +1,7 @@
 /**
  * WordPress dependencies
  */
-import { sprintf, __ } from '@wordpress/i18n';
+import { sprintf, _n } from '@wordpress/i18n';
 import { withSelect } from '@wordpress/data';
 import { serialize } from '@wordpress/blocks';
 import { count as wordCount } from '@wordpress/wordcount';
@@ -16,17 +16,25 @@ import {
 import BlockIcon from '../block-icon';
 
 function MultiSelectionInspector( { blocks } ) {
+	const words = wordCount( serialize( blocks ), 'words' );
+
 	return (
 		<div className="editor-multi-selection-inspector__card">
 			<BlockIcon icon={
 				<SVG xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><Path d="M3 5H1v16c0 1.1.9 2 2 2h16v-2H3V5zm18-4H7c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h14c1.1 0 2-.9 2-2V3c0-1.1-.9-2-2-2zm0 16H7V3h14v14z" /></SVG>
 			} showColors />
 			<div className="editor-multi-selection-inspector__card-content">
 				<div className="editor-multi-selection-inspector__card-title">
-					{ sprintf( __( '%d blocks' ), blocks.length ) }
+					{
+						/* translators: %d: number of blocks */
+						sprintf( _n( '%d block', '%d blocks', blocks.length ), blocks.length )
+					}
 				</div>
 				<div className="editor-multi-selection-inspector__card-description">
-					{ sprintf( __( '%d words.' ), wordCount( serialize( blocks ), 'words' ) ) }
+					{
+						/* translators: %d: number of words */
+						sprintf( _n( '%d word', '%d words', words ), words )
+					}
 				</div>
 			</div>
 		</div>