***SPOILERS*** Possible Identity of the 5.5 trial might be different then we expect.

[Seraphor]

My takeaway from that scene was not "Valens is not going to use Zenos' data" but "Valens is going to keep making adjustments and throwing "savages" into the meatgrinder until he gets his desired results, e.g. a "Zenos" that is loyal and obedient to him."

But he has his pilot, it's Alfonse. His experiment is to find the right data to use for the Oversoul.
If the pilot is the variable, then that experiment is completely useless. You end up spending your successful candidate in the experiment and then have nothing left for the practical application.
The obvious conclusion is that he needs the data of an obedient soldier to ensure that Alfonse doesn't betray him.
And for a prediction: Alfonse tries to turn on the Empire but Valens remotely activates Oversoul, transforming him into this obedient soldier's persona, and we have to fight him.

Zenos would be too much, we're still fighting him in the MSQ. That's why they ruled him out.

[Cilia]

But he has his pilot, it's Alfonse. His experiment is to find the right data to use for the Oversoul.
If the pilot is the variable, then that experiment is completely useless. You end up spending your successful candidate in the experiment and then have nothing left for the practical application.
The obvious conclusion is that he needs the data of an obedient soldier to ensure that Alfonse doesn't betray him.
And for a prediction: Alfonse tries to turn on the Empire but Valens remotely activates Oversoul, transforming him into this obedient soldier's persona, and we have to fight him.

Zenos would be too much, we're still fighting him in the MSQ. That's why they ruled him out.

The point is to fine-tune the loaded data so when Oversoul is activated the Zenos clone stays loyal and obedient. The genius of the Oversoul system is that it effectively allows anyone to be a pilot by forcing a consciousness derived from the loaded data into the current pilot, physically transforming them into a grotesque copy of the loaded data's original person and overwriting their consciousness. (It's synthetic auracite, and given normal auracite draws out the worst qualities of its wielder and transforms them into lucavi, this is hardly surprising.)

Valens is just throwing "savages" into tests as a meatgrinder to get the loaded data just right to the point the "Zenos" created by the Oversoul system stays loyal and obedient. He's fully aware Alfonse intends to betray him, hence why he is making the Oversoul remote activated; that way if Alfonse isn't performing as well as he wants or if (when) he makes his play Valens can just activate Oversoul and nip any attempt to do so in the bud. Valens is many things, but considering he's apparently taken cues from Hojo stupid is not one of them.

All that said we don't exactly know how the conclusion to Werlyt is going to play out. Diamond Weapon, Zenos data, G-Warrior, and whatever hidden plan Allie has are all on the table; how it all fits together is anyone's guess.

(And we don't know we're fighting Zenos in 5.5(5) yet.)