This term is an adopted standard by the International Telecommunication Union (ITU) and hence many other UN organizations. It is always a best practice to look for current standard terms before attempting to use new ones.

As an example, here are the English and Arabic versions of a section on localization from a UN document issued by the JIU (Joint Inspection Unit) titled "POLICIES OF UNITED NATIONS SYSTEM ORGANIZATIONS TOWARDS THE USE OF OPEN SOURCE SOFTWARE (OSS) IN THE SECRETARIATS":

Localization
17. The Localization Industry Standards Association defines localization as the process of making a product linguistically and culturally appropriate to the target locale (country/region and language) where it will be used and sold. Major software companies release their software initially in English. Localization is therefore indispensable for a wider dissemination. It is market driven under a proprietary software business model whereas the open-source development model allows developers all over the world to collaborate via the Internet to a localization project, resulting quite often in easier, faster and more affordable adaptations of software to suit a particular locale.



I also agree with Mona's suggested توطين as another choice because of its existing widespread use.