But if you didn’t have the NZB, is there any real chance you could find it otherwise?
No, but that’s just the nature of NZB file sharing. The individual articles aren’t typically tagged/named with the actual file names, that info is pulled from the NZB and the de-compressed + stitched together articles.
I’m not using any special indexers, just open public registration ones. The NZBs aren’t hard to find, for me or for IP claimants.