'Chikichiki' should probably be left untranslated. Yukari's line is a parody of Gaki no Tsukai's episode names.
Something the average reader may not recognize, so leaving it untranslated will be lost on them. Even if the reader does get the reference, leaving it untranslated would feel out of place to me.
I've sent her on errands to Yuyuko's, but dealing with a total stranger, and a Gensokyo human who's afraid of youkai, at that...
So starting today, focus your energies on social studies, okay?
Go buy some fried tofu from the tofu merchant who comes from the Human Village!
Oh, look at her go around and around.
Ran, in the future, I'm going to entrust you to do a lot of things in my stead.
do your best, Ran!
Round 1! Whirring Social Studies: "Can you run an errand alone?"
If she doesn't do well, he may end up running away on her.
Mishter Tofu Merchaaant
Clench
In the future, it may be necessary to have discussions with both human and youkai alike, so...