You could also look at it as putting down a storage chest so that you can run down a belt and pick up all the items that shouldn't be there, or sticking a chest next to your un-barreling factory while you work out how to get a return train back to the barreling factory, or putting down some fuel tanks to hold light/heavy oil while you research advanced oil processing (before the basic oil change).
I'm skeptical that this will fix the problem by itself, but it buys time to observe the system in action and adjust capacity on other bottlenecks to bring it back into balance.
I'm skeptical that it will increase observability. Buffering tends to hide problems, not reveal them. We know what the bottleneck is (getting empty containers off a critical location, as far as I understand.) Adding more empty containers to this critical location will not increase our ability to solve the problem, it will put off the problem into the future while simultaneously making it worse.
I'm skeptical that this will fix the problem by itself, but it buys time to observe the system in action and adjust capacity on other bottlenecks to bring it back into balance.