Changing our contact email address in Event Templates
I assume the email address you are referring to is on the location tab.  If so, the assumption is a location has a fixed email address.  When you change the email address on a location it changes it everywhere that location is used.

So you need to create a new location.  Unfortunately, location appears to only look at the address part so if you create a new location with the same address as another but a different email or phone number, it doesn't create a new address.  It just updates the existing address.

The work around is to make the address part different.  I'd suggest using the Supplemental Address 1 to indicate who the coordinator is.   You could simply put their name there or something like Event Coordinator: Name or Attn: Name.