This isn't like Hattrick, you don't need any official approval to create an application. Don't scrape the transfer list and don't abuse the API too badly, and you'll be fine.
Not my case, I won't do any abuse, that's for sure. I already started a discussion about this issue 2 weeks ago by BB mail with some officials but none of them could say for sure 'Is ok man, you can develop the too you have on your mind'.
Anyway, having this replies helped me to take the decision - I will develop this tool.
Thank you.
Florin.