Solution:

For Video Device-Enabled Meetings, where the host has specified a preferred language, the endpoint audio prompts and video messages will be localized accordingly. As an example, if a host has set their language preference as German, all attendees joining this host’s meetings from any location will be presented with a German user experience. There is no method for attendees to modify the language preference independently of the host.

Workaround: If your attendees require the English IVR TP prompt, you can add the following to your meeting invites:

'For English speaking only attendees, please dial meet@sitename.webex.com from your endpoints'.