I would like to contribute one or two translations.
Any chance you might shift to GlotPress?
GlotPress is an Automattic project for crowd-sourcing translations. This is how WordPress uses GlotPress: http://translate.wordpress.org/projects
As you can see, this means lots of users can contribute translations, and the project doesn't have to depend on any one person to provide translations after every change to text strings.
Basically, people provide translations online. You can assign gatekeepers who can verify whether or not particular translations are ok. GlotPress generates .po .mo files which your plugin (as installed in some WordPress site somewhere) can then pull these files.
Here are a couple of excellent guides to get you started (it's incredibly simple):