I just noticed that the strange display of the comma happened because I did not edit the text in source mode which is why there where some HTML tags added. I will try it now using the source mode.
Do you know how I can add an "other" answer as a condition?
This is how the set conditions editor looks on my survey. Here I can select all the previously asked questions as a condition for this question to show up. But I need it to show up also if a participant selected "other" in a previous question.