The statements "If it's complicated, it's probably wrong." and "Sometimes, problems have a complicated solution." are compatible with each other. In fact they're saying the same thing.

If a problem has a complicated solution, it is a complicated problem to begin with.

In this case, we have a much stronger guarantee of simplicity than, for example, with mathematical problems that are easy to explain but might lead into unexplored territory: a missing piece in Panini's treatise is something that he definitely figured out in his time, so it is well within the reach of today's linguists.