Great tool, however I think that source code should be separated from language project. It would be better not to create or keep localizations in Visual Studio. Using satellite assemblies localization can be created using only .dll/.exe (compiled project).
This way adding a new language does not require recompiling the project. What is more translation could be made even by the end-user.
I found localization tool called
(free for non-commercial use or buy option) which does exactly that. It is simple and has same useful features. I am not sure are there any other tools which use only .dll/.exe.