I'd appreciate a tool that would combine a lang/template/lang.php and a lang/xx/lang.php (xx language translation) file.
The idea is that lang/template/lang.php would be the template for outputing all
$lang['some_key'] = 'some_value';
lines in the order they appear in the template file but with xx language values inserted where available. When a value is not available, the template value should be retained and some warning be displayed.
An obvious choice for lang/template/lang.php would be a current lang/en/lang.php (the english translation).
In this way, it would be easy to prepare new translations, based on older ones for the same language and current english ones while, by working on the resulting merged file.
As it is now, I have to check
http://wiki.splitbrain.org/langcheck.php#el, the old el translation and some up-to-date reference file in another language so that I can do the job and it can get quite confusing at times.