Hello Edu,
it is not a bad idea to test the Trading portfolios with your broker. However, it is strange for me that only few pass the validation.
What is the acceptance criteria in the Validation that you are using?
Also, I saw the name of your broker(I do not say any brokers names in the Forum), I think you should make a good research about them, I have heard from students not really positive reviews, as they are closing the trades(interfere the traders work), no security on the deposits, and so on. However, this is a personal choice which broker you will use. What I want to say is that even you use the best EAs, they will not work at all if your broker is not trusted.
You should always try to generate your own strategies, specially once you are get used with EA Studio.
The Validator is useful because it nearly eliminated the Demo account testing. It shows the same results when you refresh your Historical data, and it is really useful tool, but let me know what is your acceptance criteria there, because this is what stopped the strategies from passing.
Kind regards,