A question for all of you experienced translators out there: is 触れた more likely to be the plain past tense of 触れる, fureru, "to be (emotionally) moved", or the potential past tense of 触る, sawaru, "to touch/feel"?

触れる can also mean "to touch", in a physical sense. I fixed up some of the translations here and added a few. That 「或る少女の為のコンチェルト」 was sort of hidden, haha. Also, Hong Meiling seems to be in this comic too, so I tagged her.

Yes. The main difference in the physical sense is that sawaru means actively touching something, while fureru means coming in contact, and includes touching things inadvertently. That's why they used the latter here.

D... damn it. This one made me tear up T^T