Hello! Can I ask what about JaneKan appeals to you? Asking genuinely since I haven't seen them together before, but it's intriguing! I like RoseMary and am happy for them, but I also think it's interesting to explore alternatives just because, well, entering your first relationship at 13 during a highly traumatic time is bound to have some complications eventually -(professor-pucefoot)
hello!
janekan is actually something i only started to seriously ship recently. janeroxy and rosemary were both previously my main picks for them, as i find them very compelling.
my thoughts on them aren't very complex: i feel like jane and kanaya's personalities make them a good match for each other.
also, similarly to what you said, rose and kanaya began their relationship in a very tumultous stage in their lives; while they made it work, i must admit i find it interesting to think about kanaya being in a relationship with another character. jane, being my favorite hs character, was my first (and very biased) choice.
tl;dr: they're both very silly. and they can be sillier together. :)