Gonna analyze the options a bit, both tactically and narratively. Also assuming barbarian stuff happens regardless cause, well it'd be boring otherwise.
[] The river villages.
This option would involve protecting the length of a valley from barbarian raiding. Mobility is still a large asset. It specifically notes Zhengui so ought to have some narrative focus there. Seems most likely place for Shen Hu to hang out. I'm a bit worried by collateral damage to the farmlands between Ling Qi and Hanyi; Zhengui can prooobably repair living stuff he sets on fire, at least. Overall narrative of this option probably focuses on the ties between people and the responsibility of cultivators to mortals. Opportunity to actually examine barbarians seems really low.
[] The messenger cadre.
The generalized support option. Mobility is the biggest advantage here. Ling Qi will be sent all over with this one, touching on various different people but not having a great deal of contact with any of them. Might actually see Gu Xiulan during the mission if we pick this. Because Ling Qi is travelling all over, and will often be alone, this is the option with the most narrative flexibility in what kind of encounters Ling Qi has, but it's also the one with probably the lowest chance of assured, direct contact with the barbarians, making it something of a mixed case. Narratively, I'd expect this to examine themes of communal responsibility and the importance of a cog's role in a machine.
Using CDE for communication is nonsense talk; developing the necessary protocols don't make much sense if Ling Qi is the only person with the art, and the range is so short it's only a few minutes of flight time. The more realistic use of the art in this context is scouting out rendezvous points to see if they've been compromised before she drops by to hand off information.
[] The front line.
This option is a bit unclear in what it involves exactly, but probably fights. Mobility might be insufficient for keeping up with a Cyan's cruising speed, even if they're not flying. Teaming up with the big boss and cruising for trouble is appealing, but I have reservations. Beyond the whole keeping up thing, Ling Qi is identifying herself as the next strongest unassigned asset; it seems tactically questionable to pair that with the strongest asset on what is essentially a speculative assignment, when there are a variety of hardpoints to defend as the mission's main thrust. It appears something of a misappropriation of resources to commit Ling Qi to Guan Zhi's side. Narratively, this choice probably gives lots of contact with barbarians, but should be very restricted in the kind of interaction we can do or even attempt while we're babysat by a Cyan sect superior.
[X] The messenger cadre.
I'll be frank, I'm still sore over the prior missed opportunity, and so I am disinclined to settle for options more likely to present barbarians in their conventional understanding. Defending a village from raids or scouring the peaks for targets to hit like the fist of The Wall are unexceptional. This is the option that carries the highest chance of the unusual, of stumbling into an out-of-context context.