It' very easy to rename object name in script.
In your case, you can modify the following code:
set tables=model.tables
for each t in tables
set keys= t.keys
for each k in keys
output k.name
output k.code
output k.constraintName
output k.name & " is primary key " & k.primary
next
next
set references=model.references
for each ref in references
output ref.name
output ref.code
next
You can reset key name or reference name using statement like
k.name=" abc"
ref.code=" ref_code"
To execute the code, open your model, go to Tools->Execute Commands->Edit /Run Script.
For more information, go to Help->Meta objects Help. Search for an object name.