Seriously? At first what happened is they just decided not to choose you as a contributor. There are way more people who are qualified to contribute than they can choose as a contributor, so unless you are a celebrated translator of Modern Greek literature with a PhD in comparative linguistics, you're just one well-qualified person among dozens, maybe hundreds.

Now, unfortunately you're just annoying them. When you apply for jobs (even volunteer ones) and ask people out on dates, no answer is an answer. You're wasting their time and yours by continuing to bug them.

As for giving you a negative answer, no. They are volunteers who are doing this for love of the language (presumably like you), and they only have so much time in a week to work on the course. Any tasks that don't directly contribute to that is wasted effort on their part. Sending out rejections is something that is almost impossible to do well, is easy to screw up, and will actually slow down their ability to create the course, so of course they're not going to do it.

How would you feel if they brought you on board and then said that your only job for the next three months was to develop an application management system that enforced rigorous and fair standards to be uniformly applied to every applicant and to handle all inquiries about the course, including sending out rejections to every applicant, and also dealing with the inevitable fallout when people aren't happy with their rejection and start writing to find out what they could do to improve their chances or to complain about not being chosen. You'd probably be unhappy, and would complain that you wanted to contribute to the course, not to be their volunteer HR rep.

When you complain that they could at least send you a negative answer, you're only thinking about the thirty seconds it takes to write an e-mail. But you're not thinking about the process that would need to be in place before that e-mail could be sent, or the likelihood of a poorly phrased e-mail creating more problems for them, or the fact that sending you that e-mail won't contribute to building the course any faster.

At this point, you're not going to be chosen. Even if you had a strong application initially, you torpedoed your chances by submitting a new application every other month regardless of whether they posted a specific call for applications. Join their facebook group and participate their, and once the course comes out beta test the shit out of it.