How to load Voice "en_GB-cori-high" to Piper - Unavailable in Piper config but works in Assistant responses

Your help would be appreciated please.
I’ve just set up the full Voice experience, and have everything working flawlessly (thank you all!) apart from one thing. My speakers are sub par for my ears so I’ve been looking for a higher pitched voice to overcome the “muffled” output lower pitched voices seem to produce.
en_GB-cori-high appears to be perfect from playing the samples through them.

However neither en_GB-cori-high nor en_GB-cori-med appear in the list of voice files available to Piper. Cori does appear in the Voice Assistant config under Text to Speech for the responses, and works well there, so I’m fairly sure the cori data has downloaded successfully.

Editing the name directly into the Piper config’s YAML also fails with an exception because en_GB-cori-high doesn’t appear in the list so the helper is preventing me saving it.

Does anyone know how I can convince Piper to accept a voice that’s apparently already downloaded please?

Hardware: Odroid N2+
Google mini speaker for automation triggered speech output
M5Stack Atom Echo for input/reply to Voice
Core: 2024.4.4   Supervisor: 2024.04.0   Operating System: 12.2   Frontend: 20240404.2
Piper: V1.5.0 

Opened Issue : Piper won't select en_GB-cori-high voice · Issue #117262 · home-assistant/core · GitHub