“Sphere Client Locale Forcing Mode
With vSphere 5.0, you can configure the VMware vSphere Client™ to provide the interface text in English even when the machine on which it is running is not English. You can set this configuration for the duration of a single session by supplying a command-line switch. This configuration applies to the interface text and does not affect other locale-related settings such as date and time or numeric formatting.
The following vSphere Client command causes the individual session to appear in English:
vpxClient -locale en_US”
as per release notes in vSphere 5.0