Keyboard Maestro “Append suffix '-ation' to typed word” Macro
Thanks to @peternlewis for helping me to capture the end-of-word marker.
The macro is designed to be triggered by a word ending in consonant+n
([^aeiou] in RegEx means 'not vowels')
Users may need to modify the string to suit themselves. I have added r and w to deal with words such as born; torn; own; down; grown etc.
It should be put in a group that excludes Finder just to avoid any unpleasant accidents.