Are the DAP system exams really recognized?

The DAP (Diplôme d'aptitude professionnelle) is recognized in Luxembourg and across EU countries for vocational training - it's not some made-up thing. That said, how much it's actually worth really depends on the sector and which country you're planning to work in - it works fine in Belgium or France, but elsewhere you've got to check with the employer or training organization. If you're aiming for a specific career, just ask the companies or schools you're interested in directly, that'll be clearer than a general answer.