Pneumonectomy refers to removal of the entire left or right lung, yet the example you give is after a right lower lobectomy. Instead of pneumonectomy do you mean lung resection or lobectomy? You quote BPF after pneumonectomy in the introduction, but I don't think that is what these patients had.

If you are referring to BPF after a lobectomy, that is pretty rare. I'm confused why you have such an extensive collection after lobectomy.
By fistula location, I would change "superior bronchus" to "upper lobe" or "upper lobe bronchial stump". Use upper, middle, and lower for consistency.

Table 1 should also define what the original surgery was.

Small BPF (SBPF) is a new term defined by the authors (beyond the visual range of a bronchoscope) and is not a standard term used in other journals or articles. If it was not visible by bronchoscopy, how do we know it wasn't just a parenchymal-pleural fistula (ie regular airleak). A lobar bronchial stump leak should be visible by bronchoscopy. Because of the confusing terminology, I'm not sure exactly what you have been treating. If the bpf wasn't visible by bronchoscopy, how do you know it was a bpf?

Can you explain how the negative pressure was applied? If you put a suction tube near a bronchopleural fistula, it will constantly suck air. This can actually steal air from the patient and make them respiratory insufficient. What level of suction was applied? What happened if it sucked too much. The example you give, the initial ct scan shows a large pneumothorax not an abscess cavity. How was the pneumothorax treated. How did you get the airleak to stop?

Were there patients who had bpf that this technique didn't work for?

I don't see that there was anything particularly novel about the technique you are describing other than the drain was left in place for a long time.

To accept this paper I'd have to have a better understanding of what post-operative problem these patients had and then how the airleak was handled.

I find this paper misleading. It says bronchopleural fistula after lobectomy, which means a fistula to the bronchial stump. Instead, however, they are describing a fistula localized to the remaining lung - "to the segmental bronchus, bronchioles, or part of the lobar bronchus."
"In 16 patients, it was confirmed by bronchography that the fistulas were located in the bronchus rather than the lung parenchyma." Which bronchus? They need to make clear that this was not the bronchial stump. "There were two cases of lobobronchial fistula, one case of segmental bronchial fistula, and thirteen cases of bronchiole fistula." So clearly the airleak was from the remaining lung. Big, big difference. Therefore I would not describe these as a bronchopleural fistula. This is an parenchymal-pleural airleak or fistula to the remaining lung with empyema after lung resection.
Also, they don't describe if the amount of air suctioned through the tube caused problems. If there is a large airleak, the patient can become respiratory insufficient. Should include at least a line about that.