Urethane is kind of weird. It's a plastic, but the plasticisers tend to migrate less than PVC, which is why the hypalon glue works at least OK on it. Ideally, you'd use a couple of layers of urethane glue on the urethane, and a couple of layers of hypalon glue on the hypalon, then stick the differing glues together. But, as long as the glue has adhered to the urethane, why worry about it?
As far as the dissimilar materials, that won't matter as long as the glue joint is secure.
I find it interesting that a boat called a "Eurovinil" would be something other than Vinyl. But that might be just me.