The point at issue isn't so much a legal one as it is one of proper communication.
Most of the civilized world uses the word "evidence" to refer to signs of some particular activity or behavior or process. A dentist finds evidence of tooth decay, a home inspector finds evidence of rodents. The word in common usage is pretty broad.
But when talking to a lawyer, you say the word evidence, and she mentally appends "of criminal wrongdoing" without you putting the words there, because in her practice, that's what "evidence" always refers to.
So if, in analyzing a compromised system, you point out that there is some evidence of a failed login attempt at 7:35 UTC, she's possibly going to assume that you said there is evidence of an unauthorized break-in attempt at 7:35, when in reality you said no such thing. You simply said that someone tried to log in and failed, and you noticed that fact in the logs. The logs make no mention of whether or not that user had authorization to access the computer, and you have not done any additional follow-up work to determine whether that was the case. That is, the facts you uncovered are not necessarily the sort of "evidence" she's after, and you don't want to suggest that you have already determined them to be relevant.
So to save both of you a lot of misunderstanding and potentially some serious embarrassment in the courtroom, you avoid the word "evidence" because it has a special meaning to her. This is the sort of advice that is borne out of frustrating experience, and not a bad idea to follow.
Whether the examiner will personally get into legal trouble in such am instance isn't clear, nor do I think that's necessarily the implication. But you could certainly spark a misunderstanding which could damage the case in court, and that's worth considering.