This would normally be handled at the system level in linux. (and I suspect windows as well, but I've never used any gnome stuff there.) Copying just meld's translation files isn't sufficient, as meld is depends on translations
from the rest of the gnome system as well.
On linux you would typically go through the system settings/control panel (`gnome-language-selector` or something like that) options for language/locale to install and set what language you want to use system-wide, and
gnome applications like meld will automatically pick that up and use the correct translations.
You can also override the locale for a specific application via the environment, if you want a particular app to use a different language than the rest of the system. In that case you need to make sure the language files
are already installed, though...you'd need at least the `language-pack-gnome-de` package and any dependencies, maybe some others too. Then you could launch meld in german like:
