I am sure this is a bug. Though there is a simplified_chinese language file in the SVN directory but the rsgallery2.xml file for installation doesn't contain the install comand/sentence for this file. So I added a line as following to the language secton in the file and then tried to install it on my testing server.
<filename>language/simplified_chinese.php</filename>
But there comes the following error message:
Warning: com_install(W:/www/joomla/administrator/components/com_rsgallery2/language/simplified_chinese.php): failed to open stream: No such file or directory in W:\www\joomla\administrator\components\com_rsgallery2\install.rsgallery2.php on line 17
Warning: com_install(): Failed opening 'W:/www/joomla/administrator/components/com_rsgallery2/language/simplified_chinese.php' for inclusion (include_path='.;/usr/local/PHP/includes;/usr/local/PHP/pear') in W:\www\joomla\administrator\components\com_rsgallery2\install.rsgallery2.php on line 17
At the same time all those entries which I had translated show up as original code instead of human language. See attached screenshot for clear understanding.
I looked into the server directories, suprised to found that the <joomla>/administrator/components/com_rsgallery2/language folder is empty ! No language file exist there, no one, just empty !
why ? why those language files was not uploaded when installing ?