@Meathead
It’s really a rather easy thing for a scripting plugin to do, as Peter says.
Here’s a demo using PythonScript; see if you can follow its logic without further explanation:
from Npp import editor
city_string = '''
Sydney
Melbourne
Adelaide
'''
city_list = city_string.splitlines()
city_list.pop(0)
for city in city_list:
editor.replace('city', city, 0, 0, editor.getLength(), 4)