Origin use "\r\n" for new line, so add the CR character, or replace like the following:
WorksheetPage test = Project.WorksheetPages("Book1");
string str=
"Buddy, you're a boy, make a big noise\n"
"Playing in the street, gonna be a big man someday\n"
"You got mud on your face, you big disgrace"
"Kicking your can all over the place, singin'\n"
"We will, we will rock you\n"
"We will, we will rock you\n"
;
str.Replace("\n", "\r\n");
test.SetComments(str);
Assuming you have no issue with using string instead of char [].
CP