it's not a bug and you are misinterpreting your stats. Highest trained means what language you have trained to the highest level, and not a level of the most difficultkata you have solved.

I was running into this issue initially(solving in Java). It could be using the frequency method in java to essentially assert that the 3 words in the returned array "appear" that many times in the input string. My hint to you is make sure that you are replacing all posiblle delimiters correctly. You can pass the inital sample tests because the input strings do not contain delimiters "sandwiched" between two words (eg. "word word word(some delimiter)word"). Remember a word is a defined as a string of characters (a-z) that can contain one or more apostrophes.