There are no problems from my side in being unable to translate langconfig.php, however not sure to get if the lanconfig.php will be centrally edited to satisfy local language conventions which differs from country to country.
I recall in the past I had to change some lanconfig strings to adhere to Italian language conventions, from simple things like 24 hours format to more complex adaptation of date shown in several parts of Moodle, such as logs.
If conventions will be adapted centrally by HQ, I'm happy to keep lancongif non editable by translators.