For the latest version (.48) there is an error message during install about missing language files.
These files are listed in the xml file but have not been included in the zip file for gwejson

<languages>
<language tag="en-GB">language/en-GB/en-GB.plg_system_gwejson.ini</language>
<language tag="en-GB">language/en-GB/en-GB.plg_system_gwejson.sys.ini</language>
</languages>