[causal]

Your test is a good one but the point still stands that a novel dataset is the next step to being sure.

[dontupvoteme]

One could also programmatically (e.g. with nltk or spacy, replace nouns, named entities, etc) modify the dataset, even up to the point that every test run is unique.

You could also throw in vector similarity if you wanted to keep words as more synonyms or antonyms.