Redirecting is possible, but is very likely to create buffering issues. Printing after every line can cause possible problems if either there are buffering issues, or if 2 questions are asked in a row. There is also the possibility that at some point it asks a non-yes/no question, in which case you need more logic. Try my suggested hack, if that fails you should be able to see the question it trips up on.

About using an API, I know what legacy code can be like but you still can do it. Just put a well-named function call in that line, and go off to write your function somewhere however is best. Then the legacy code is no worse, and you're free to write that function however you see best.