Error saving process model

Save Error: 

• The process model must have a valid name in the site primary language: English (GB).

Switching the primary language setting (in admin console) to en_GB causes all my process models (in other applications) to show "???", so I must stay 

with en_US as primary language.

 How can I fix this process model to expect en_US names rather then en_GB names and let me save it ? 

Thanks