The following is just my opinion and you all may have other ideas.
The recovery was unsuccessful. The hunt WAS successful to him because I'm sure he learned a thing or two. Also, he was able to get a shot on a live wild boar not once, but twice.
The brush became impenetrable and he wasn't able to get the hog. Texas brush has thorns we can't imagine in deciduous forests!
A slightly high shot on a hog will leave you looking for a long time if you find it at all. The fact that he searched for 30 minutes just to get a blood trail at all is telling of the effort he put in to find this boar. Most people would have stopped after a few minutes without locating any blood.
He then crawled into a pig tunnel through the brush UNARMED to try to recover the animal. I believe he worked hard to recover this pig. In my mind, the hunt itself was successful.
If you have ever shot a hog with a bow, it is WAY different than shooting a deer. They have a will to live and a toughness that FAR surpasses a whitetail.
I watched a 200 pound hog trying to pull my arrow out of it's side a full 50-60 seconds AFTER I double lunged it! I have never seen an animal live that long after having both lungs taken out. I have 3 witnesses to testify to it. There were right there with me and we watched the sow go into the ravine and try to work the arrow out of herself.
Upon autopsy she had been, in fact, double lung shot and still lived roughly a full minute. Bottom line...pigs are tough and less than perfect shots lead to a recovery rate far worse than deer.
Whether or not you consider it a success, he does. Only he knows how much was learned about tracking or hunting wild pigs during this outing.