Translation:She certainly was not silent during the conversation.
This is another one when it appears as select a word gives multiple options that form good esperanto sentences. I was lucky enough that it seemed most likely the answer would be in the past tense, but I can also imagine situations where one could say she is being silent during the conversation or that she will stay silent during the conversation to come.
I don't know what the solution to this problem is, but it does mean that people are forced to guess which of the good options is the one accepted. And when you're trying to do Test Out on the computer, it's rather frustrating to lose a heart because of essentially random chance.
Without knowing what the alternatives you got were, there's no way for anybody to know what went wrong. I got 'spekti' and 'silentis' and it's obvious which of the two is correct.
Where you're given multiple answers with multiple correct answers, you're meant to choose all those which are correct. If there's an error, you're meant to report it. The course creators do try to make the course correct, but they do make mistakes, so if you come across an issue, hit the flag icon and report it. Complaining about it here won't guarantee that the course creators will see it, but flagging the issue will, even if it takes a while.
Yes, I did flag it and that's probably why you had 2 choices of which one worked, whereas when I did this sentence there were 3 answers which could have worked. Please also understand I was one of the first ones to complete the whole course, but by around that time, I was somewhat astounded by the number of these cases where I was asked to select a word, but many times there was more than one answer that made grammatical sense.
So I was perhaps bit frustrated by that and hoping maybe that by not only reporting the issue, but also by putting it sometimes into threads, the course creators would become more aware of the issue and perhaps one or more of them might take some time to look through the lessons of further instances of this problem.
I don't know exactly what caused the problem, but it was more than a single event and I believe that most times I flagged it and tried to explain what was going on.