TBH I personally think calling them yanderes is totally missing the point. Neither of them show the obsessiveness or crazed possessiveness that marks the classic yandere, to start with. But more importantly, it's clear that both of them are basically the archetype of the highly-trained, hair-trigger assassin type, put in a completely different context (girl-girl romance). All the stuff they do, if you remove the battles, would not be out of place in any issue of Yuri Hime or Hirari.
Violence is their language, but to me it's in a much different fashion to a typical yandere.
Fair enough point. I think they do show some possessiveness though. The parts where they tried to kill each other chapter 1 simply because they liked the other one and thought their feelings weren't mutual as well as the extreme jealousy on their date are definitely the sorts of actions a yandere character would take.
To make a proper judgment over whether they're actually yandere or not we'll probably just need to be patient and wait and see how the story continues to develop. Though the satire point aoinokansei brought up is also completely valid. (And in the end whether they're yandere or not I think is actually mostly irrelevant anyways. The story is hilarious yet adorable regardless.)