Include the slug transliteration plugin into the core of GS

[mvlcek]

Thus I'm more for str_replace with array using assignment operators.
But if you already use strtr succesfully, I have nothing against this way

Now that you mention it: I didn't try it and I suppose it won't work with UTF-8 :-(

However, I would still define the translation as described above in the language files (no additional variable, translate plugin works, ...) and then split it into arrays using a UTF-8 function.

PHP: the greatest pains are utf-8, the automatic escaping of quotes and finding out, if the string/array is the first parameter or not in a specific string or array function. Feel free to add to this list ;-)