I have been in close contact with my colleagues in the localization field and developers of all types for over 5 years. I do not claim to be completely objective and to bear the ultimate truth, but I would still like to share my observations.
The best result is usually achieved when the developer has their own person responsible for internationalisation and localization because it is very important for the specialist to be familiar with the internal processes and features of the development of the product. It is this person that is the link in the chain between different departments and performs the duties of someone who actually cares. A good localization manager does not just build processes in a way that stops everything from falling into a deep black hole but also chases those who make mistakes and forces them to correct them. Why do I say that they force the corrections to be made as opposed to making them themselves? That is because teaching employees to do things in the right way is the foundation of a process that has been set up correctly. Of course, the localization manager does not have to do that and they can correct the mistakes by themselves and that is also a process. But is it the right one?
The results are usually worse if the developer only works with an agency. In no way do I insist that the managers from agencies are worse than in-house managers from the company. But there is one “but”. A manager from an agency usually has a plan and a volume of work from their employer, so they are unable to give as much time to the solution to all of the issues and questions arising with each project in the majority of cases. This is not the fault of the manager or the agency. This is part of the very nature of business. Agencies must sacrifice something to maintain profitability.
It is most frequent for the worst results to be achieved if the developer decides to carry out localization by themselves or by using crowdsourcing. I am obviously not talking about those companies where the product managers are incredibly experienced in bringing their products to the international market. We are talking about the average company, where 99% of the employees know any foreign language at the level of a non-linguistic university at best. That is when a product localization is most likely to descend into complete and utter chaos which will take a long and expensive time to correct.