Best answer by Mathis
You can find an overview of your reports here. We currently don't cover copyright related questions on the forum, however I can see the track that got blocked most recently, which currently seems to be the only track that could lead to a strike if you cannot provide proof you have permission to use the content.
Setting tracks to private won't guarantee you won't receive a strike, so I'd recommend to not upload or keep any material that contains copyright protected material.
For more info around copyrights at SoundCloud, please start here on our Help Center.
Also, this blog entry might be an interesting read on the matter (though the article is a bit older, it still applies in its general concepts).