After installing the quickstart package for Joomla 3.x, I translated the language files of SJPlus template into Spanish, and I modified the file templateDetails.xml in the following way:

<languages folder="language">
<language tag="en-GB">en-GB/en-GB.tpl_sj_plus.ini</language>
<language tag="en-GB">en-GB/en-GB.tpl_sj_plus.sys.ini</language>
<language tag="es-ES">es-ES/es-ES.tpl_sj_plus.ini</language>
<language tag="es-ES">es-ES/es-ES.tpl_sj_plus.sys.ini</language>
</languages>

Of course, I've created the folder es-ES within / language, and I've copied the two translated files, but I can not see the administration of the template in Spanish.
Do I have to change something else to get it?
Thanks for your work.
Adolfo