Aaaah, yeahh.. the dub edits out a lot of the JackxCarly proof. @_@ JackxYuusei is definitely dominate in the dub. xD; & They do understand each other better, I agree. They've been through a lot together and what not.
I originally found Carly annoying, but then she and Jack grew on me as a pairing, and in the Japanese version they confessed to eachother. D; Sadly, they're as canon as Yugioh has ever gotten, aside from maybe Johan and Judai in GX.. :/
Although, with the current episodes.. any JackxCarly-ness is dead. The newer episodes seem more for the JackxYuusei fans, with Carly having such a small role.