Improving a wordpress plugin from Joomla 1.5 to at least one.6

Language files, which labored in Joomla 1.5, don't appear to become working:

This is how they're defined within the ini:

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

The word what file is situated in administrator/language/en-GB

I've upgraded it to Joomla 1.6 format with the addition of double quotes around arguments etc. (This is actually the full text:

Please can someone produce any pointers on where I am failing here.