中 / 英 / 繁 三种语言包在 Laravel5.4 死活只能相互切 2 中，求大神指点一下蒙圈了？

中间件代码
`class Language
{
public function handle($request, Closure $next)
{
if($request->session()->has('language')){
App::setLocale($request->session()->get('language'));
}else{
App::setLocale(Config::get('app.locale'));
}
return $next($request);

}

}`
//前端页面设置语言包

 <span>
      <a href="javascript:void(0)" onclick="changelanguage('zh_CN');return false;">
                 @if(\App::getLocale() == 'zh_CN') <span style="color:#1088C6;">中文</span> @else 中文 @endif
     </a>
</span>
<span class="title_content_right_shu">
        |
</span>
 <span>
      <a href="javascript:void(0)" onclick="changelanguage('zh_TW');return false;">
               @if(\App::getLocale() == 'zh_TW') <span style="color:#1088C6;">繁体</span> @else 繁体 @endif
      </a>
</span>
<span class="title_content_right_shu">
            |
 </span>
 <span>
        <a href="javascript:void(0)" onclick="changelanguage('en');return false;">
                @if(\App::getLocale() == 'en') <span style="color:#1088C6;">English</span> @else English @endif
        </a>
 </span>
 <script>
function changelanguage(val){
        $.ajax({
            type:'get',
            url:  '/change_lang',
            data:{
                '_token':"{{csrf_token()}}",
                'lang':val,
            },
            dataType:'json',

            success:function(data){
                console.log(data);
                 location.reload();
            }
        });
    }
</script>

路由:Route::get('change_lang','IndexController@set_lang');
控制器:

public function set_lang(Request $request){
        if($request->ajax()) {  //Ajax请求访问
            $lang = $request->all();
            $lang = $lang['lang'];
            \App::setLocale($lang);  //配置默认语言
            $request->session()->put('language',$lang);  //存到session
            $seccess = array(
                'code'=>200,
                'data'=> \App::getLocale('language')
            );
            return response()->json($seccess);
//            return \App::getLocale();
        }else{
            if($request->session()->has('language')){
                $res = $request->session()->get('language'); //获取session
                $seccess = array(
                    'code'=>200,
                    'data'=> \App::getLocale('language')
                );
                return response()->json($seccess);
//                return $res;
            }

        }
    }

app/config中配置的语言:

'locale' => 'zh-CN',
'locales' => ['zh-CN','en','zh-TW'],
/*
|--------------------------------------------------------------------------
| Application Fallback Locale
|--------------------------------------------------------------------------
|
| The fallback locale determines the locale to use when the current one
| is not available. You may change the value to correspond to any of
| the language folders that are provided through your application.
|
*/

'fallback_locale' => 'zh-TW',

每次点击切换语言包都能切换
dump(\App::getLocale());
但是模版中

{{trans('index.research')}}

问题:切换中和繁体 字都显示繁体
lang中都已经配置各自的包了如图:，在线等......