Putting this stuff in "SOURCES" breaks compilation for Harmattan platform, so I suggest using simply "OTHER_FILES", though it isn't working properly with lupdate, so you still need to use this simple hack to get lupdate to work.
huellif, could you someday explain internationalization in QtQuick? I was able to generate .ts file, but I have no idea, what should I do with it after that, not counting putting translations in this file. They simply weren't loaded.