All Suffusion-versions come with two files in the translation-folder of the theme:
suffusion.mo and suffusion.po
If you want to update an existing language file, you have to bring the new strings from suffusion.po into your language.file.
The way Sayontan described that process in the section "How to Create Your Own Translation" at http://aquoid.com/news/themes/suffusion/translating-suffusion/ here, is misleading.
As you have to use POEDIT to edit the language files, POEDIT is the correct tool to merge the new strings from suffusion.po into your language-file and that is very easy, it takes only 2 steps:
1) open your language file, for example de_DE.po in POEDIT
2) Catalogue => Update from POT-FILE: choose: suffusion.po (Do not mind, the correct file-extension is PO and not POT here)
after confirmation, the missing, new strings will be merged into your language file and you can start to edit it.