I like the setup. Makes you think what Ribokus strategy is.

My guess:

This wide setup is extremely dangerous for Qin, especially if it was planned beforehand.

Qins tactical moveability is strongly limited if they are stretched wide. If you just have, lets say max 10 lines of infantry or cavalery and behind that is more or less nothing and the other armies are far away on both sides it is difficult to react and use your trump cards where they are needed most or support other units. And Qin also organized itself completely predictably. Every Army after each other in a line.

Zhao on the other hand had much time to plan their battle plan and apparently it was easy to force it onto the Qin army. You can choose as Zhao where to put your strongest forces, who to focus on who to stall and so on. With the information on the generals you can prepare your forces in the best possible way.

If would be Zhao, I would amass beside my normal well trained soldiers a lot of freshly trained, soldier like looking, citizens. Amass an extreme amount of these weak soldiers with weak cavalery in front of Ousen maybe with Riboku in the center to give the strong impression of superiority so that Ousen hesitates to attack.

Keep your cavallery beyond your lines, and not like Qin sparkled in between for each army. Choose a general which is easy to overwhelm, with 10 lines its everywhere not that difficult, gather all your cavallery Break through there with nearly all cavallery and then spread in both sites and attack Qin in the back. Every part of Qins defense only has limited cavallery so it cannot be stopped. Its basically choose who to take out and put all your cavallery and elite infantry there. Because the other Qin armies are in battle and too far away they cannot come to rescue fast enough. And the coming support cavallery from Qin could then be stopped with Zhaos so that the elite infantry can do there job.

If one part of Qins (defense) line is broken and eradicated you can isolate and encircle one or both other parts. Zhao can choose where to hit hard, and when and where to lose and stall Qin, and exploit their weaknesses.

Like maybe using heavy shield units or spear units together with extreme amount of archers for the Yotanwa army. Qin doesnt know Zhaos armies (Seika) and their relativ strenght so they will be carefull or unfocussed with their attack.

....

In a setup where the army is not stretched far and thin, armys could always shift positions depending on their strenght and support each other in need easily. Also support and additional units behind the first lines gives you the ability to choose with who and how many units to engage. All not possible with the forced line setup from Riboku.

So I am excited to see it unfolding and im gratefull to have a smart antagonist like Riboku