The passage's use of the words 'could,' 'may' or 'usually' makes the statement low modality, or of low certainty. If something is 'usually' required, we can take this to mean it is required the majority of the time, but not always. The question states that, 'expert-level knowledge is required,' which is high modality, or a certain statement. You will need to get used to the fact that high certainty statements cannot be satisfied by low certainty evidence and thus the answer will be False.
Can't Tell means there is not enough evidence in the passage to prove or disprove the statement. However, we can disprove this statement as expert level knowledge is only usually required, not always required.
In reference to sevun's examples:
1. This is false. We know from the passage that X will not certainly occur. It is not Can't Tell because the passage has proven that X is not certain, directly contradicting the statement.
2. This, to the best of my knowledge, is Can't Tell. We don't know whether the claim is truthful or not. However, there is nothing to say that X didn't occur, either, making it not False.
The difference between 1. and 2. is that 1. includes the word 'certainly', and this certainty was contradicted by the passage. If statement 2 was instead, "According to the passage, X certainly occurred" this would be False. (I think)