Interesting. So you had testicle ceviche? The guy in the article described the taste as cross between tuna sashimi and raw octopus. I love tuna sashimi and raw octopus. I can eat that all day, every day. So if it's anything like what he described, I know I will love testicle ceviche. But I've also eaten chicken gizzard. And it taste nothing like tuna or octopus. The chicken gizzard is really chewy with strong rich dark meat gamy taste.
Been years since I tasted it and so didnt describe the flavor but the texture of the raw pieces that I had were much like chicken gizzard. I love octopus also and I would agree with you that it didnt taste like that but felt similar in the mouth.
Ive had other testicles but they were all deep fried and hence all tasted pretty much the same and much like deep fried chicken gizzards. Chicken gizzards made in soup pretty much lose their flavor and you are left with just the chewy texture.
Ive had turkey fries also and they were quite good.
Hope this makes sense to you. I tried. LOL Ill bet you will love the bull balls if you try them. I lived in Montana and visited Wyoming for many years. Quite popular there as yiu can imagine.