Dear Indraneel,
My apologies ( I never work in this scenario, but trying to help you ).
As per my knowledge ,We can make status update through RFC ( check the below link and program for demo) if EM and QIE are not connected ( if it is not available in standard ).
SAP Event Management - Supply Chain Management (SCM) - SCN Wiki
In your case, I think Enhancement or Background job program in EWM (QIE) required ( if It is not available in standard ) to update EM .
Hope It will help you.
Thanks
AR