I recently played Specter and noticed that some monsters could imitate. It would often reuse words or things we chatted, but would also seem to form it’s own sentences. I would like to know if there is more to this or if it’s just those two systems.
I would like to make a good imitation system for my horror game.
Look into a MadLib generator its a really easy thing to do and I am confident that is what the game uses based off of what you are telling us 
MadLib Definition:
A Mad Lib is a word game where participants fill in blanks in a sentence / story template with nouns, verbs, adjectives, and other parts of speech. The goal is to create a sentence/story based on random word choices.