Posting as no idea if this is just a stupid netsuite thing or our config somehow??
We have EN FR and DE language customers, there's a few text blocks on some transaction advanced pdf templates that are more easily hard coded than managed through fields. As only ever those 3 languages not too painful to do "IF DE .... ELSEIF FR ..... ELSE..(EN)" etc.
Odd thing is using the same German language customer on a Sales Order template
record.entity.language = Deutsch
but on a packing slip template
record.entity.language = German
Same is true of FR coming out as 'French' or 'Français (France)'