Are you talking about the console of the Core Server or of a remote console on another client?
Also, did you do an upgrade in place (Same Core Server) or a side-by-side upgrade (New Core Server)?
I'm talking about the console on a client.
The console used to be in english but as I did the upgrade from 9.5 SP2 to 9.6, all the menu are now in french and I had no possibility to configure the console in English from the upgrade wizard.
On the core server, the console stayed in English.
We did an upgrade in place.
Thanx for your support.
For the Remote Console, please uninstall first the 9.5 console via Control Panel, and reinstall the Remote Console on the client and you can choose the language.