I had to take 3 of the 14 tests about 7 years ago to get my Turkish validation. They have a test question database, and my company provided me with a computer program to teach me / test me and work through the weak areas. I had about 2 weeks to prepare for the three tests, and it was more than enough. Don't remember the grades I got, but I scored high on all three. There was a fee for taking each test. My company paid it. So you're going to incur some costs for computer prep, test fees, EASA medical and of course sim ride in your current equipment. But I don't think the tests are anything to fear.