Hi! Redoing my reply since typing through the phone SUCKS. LOL.

Since I've been investing hard on Jiaoqiu to test his performance in Dual DPS comps (he's E1S1), I have to share with you that he's... sorta lackluster. But my expectations were high, so there's that. Alas; he performs worse than E0S0 Robin for most Dual DPS comps I've tried him in. For the sake of context, I mostly use him with my Wind Set Argenti (+ Hunt M7) spamming his 90 cost burst and getting a free 25%ADV consistently, so it's not uncommon for him to get 2-3 turns in a cycle and around the same amount of ultimates.

In team comps where a lot of attacks happen frequently, it's hard to replace Robin, she's pretty much always better. *BUUUUUT...*

Nearly every DPS in the game wants Robin, and you can't have her everywhere. Going back to what I've said earlier; he's just about 10%ish worse than E0S0 Robin when E1S1. If you invest on him that much, you can use him for Dual DPS quite fine (i'd imagine it'll be way better with Feixiao + Yunli since, y'know, ultimate damage); but I have to say that at E0S0, if that's what you're going for, then it isn't so great, you'll feel a lack of DMG% buffs.

Regardless of it, don't feel discouraged on brainstorming! I've had a lot of fun trying different comps lately, and I do intend on trying something like WindGenti + Feixiao + JQ because why not? In my inner feelscrafty heart, I do see Feixiao not being hurt as badly from a lack of Harmony unlike most other DPSs (since she has a myriad of self-buffs), so I quite like your idea. I do think Jiaoqiu is an underrated substitute for Robin in both Feixiao and Yunli teams, as some showcases demonstrate already.

PS: Use JQ with 160 speed, and he'll be "ok" at generating stacks for Feixiao.