Update: The artist has gotten back to me with the completed commission and the following claims.
The email was not responded to earlier as it was in their spam folder
The commission was sent out "last year" (2024) to the "email associated with your initial invoice". Given that there was no invoice and payment was done at the con, I do not know what this means
They had marked the item as done on "their list", which would have to be something that's not the Trello that hasn't been updated
They no longer have access to their Telegram account and recommends blocking it. There has been no mention of losing their Telegram anywhere on their other social media
With that, I believe this could be considered a resolved incident, but hope this timeline could help others be aware of what level of service they sign up for with this artist.