[Used Can]

I believe an explanation for this is that the kids at Fukuin are probably taught English. Of course, I don't think nothing like this has ever been hinted, unless there's something I don't remember. But, either way, we've been told they've received education there. So, it may not be wrong to assume this much.

In addition to that, the Epitaph wasn't released until 1984, which happens to be the same year Kanon "arrived" to the island. Unlike Shannon, who, by now, we know is almost surely one of Yasu's imaginary friends and/or personas, Kanon remains a slight anomaly, since we never really saw him in Yasu's memories, which I think is rather suspicious. In addition, they way he came to be was rather weird. So, I think this can be seen in many ways, like Kanon being Kinzo's actual offspring (and not one of Yasu's creations), or him being someone Kinzo entrusted his child's (Yasu/Lion's) care, Kinzo not recognising his child until he looked like a boy, or Kinzo never actually met Yasu until (s)he was playing the Kanon role. Either way, Kanon's appearance in the island may, or may not be related to Kinzo releasing the Epitaph, and I believe this is too big a coincidence to believe they are not related.

Something that I believe should be pointed out is that the Epitaph was probably written even before Kinzo and his family moved to Rokkenjima, since the chapel has been there since mansions' creation, and I'm sure the secret mechanism has been there from the very beginning as well. So, this Epitaph may be unrelated to Beatrice and/or Yasu. In fact, in Lion's world, Kinzo didn't even release the Epitaph, until the siblings started complaining about Lion being the successor to the family's headship. So, Kinzo using the Epitaph as a test to find this kid may be just one of Kinzo's many bets.

As clichéd as it may be, I don't think the line "I wouldn't out it past Kinzo" has been there for nothing. We've been told many times not to expect common sense from him. Of course, along with that, we've been also told he's a very intelligent man, a genius. So, in this case not expecting common sense from him doesn't mean he's stupid, but him having his own way of thinking which, whilst it may look nonsensical to others, it makes sense to him. Therefore, this may be taken as one of Kinzo's big bets.

Of course, as I pointed out, Kinzo releasing the Epitaph coincides with Kanon's appearance, meaning that there are chances Kinzo was aware of his child's presence in the island. So, he made that bet. If that child solved the Epitaph before anyone else, he'd tell him/her the whole truth, apologise to Beatrice, and appoint that child as the new head. However, if anyone other than that child solved the Epitaph first, then he'd probably give up on that child and give the headship along with all the belongings of the Ushiromiya family to that person, whoever that person may be. This may be the reason why Genji gave some clues to Yasu, so that Kinzo's bet would succeed.

I'm sure I've made some rather big stretches on several points, but I think that, for Umineko, this much makes some sense.