I wouldn't use this forum as a basis to determine a failure rate, although it can be a good reference for things that are popping up. If the majority of CX-5 owners were on the forum we'd have tens of thousands. Instead we have a couple dozen active users (cx-5). For plenty of people who don't really use social media (maybe they have a facebook at most), aren't familiar with forums, or mostly, aren't enthusiasts the fact that something broke may be the only reason they show up here, because they found it specifically while searching for someone who may have the same issue. It's like me mentioning OVT here. If you go to the correct circles (multiple forums and FB pages), it's a known and respected name. I mention it here and people don't have a clue, which also let's me know at least 6 or more major mazda outlets they probably don't participate in as well. It's easy to sit here saying how this hasn't happened to me nor has it been reported, until it's happening to you and you have users downplaying the situation based on limited feedback.
Check out the Focus dual-clutch threads, hundreds and hundreds of pages relating to that fiasco, resulting in a class action lawsuit. Now that's a faulty transmission.