Someone please check my work on the last 3 bubbles.

I think the gist of the joke here is that it sounds like Kagami is saying she brought the chocolate cornets because she likes Konata, but what she really meant is that she has them because Konata likes them (she says "it's because of like" which could be interpreted either way since Japanese typically leaves out petty details like pronouns).

You picked up on the joke correctly and I don't see an easy way to translate it. Kagami's line 好きなんだから can mean 'because I love you' and 'because you love them' simultaneously which doesn't transfer well to English.

Translation edited and tag updated.