Before I answer what is necessary to be reliable in treatment of Chagas disease, I'd like to clarify what the curanderos (indigenous medicine men) deem as reliable. Their reliability is based on observing symptoms, less stringent of what we measure in the states. We know symptoms may go away, but recur after many years, even decades later, and death may be assigned to a different, and potentially incorrect cause. Studies do exist supporting the use of Neurolana lobota, however, the route of administration (oral) and preparation (tea) may be ineffective to fully eliminate this pesky parasite. The evidence we need would need to be facilitated by random controlled trials. Unfortunately parasite is in makes one's body home for the long haul, therefore these studies would have to extend over many years. This lengthy experiment would require many resources, and I would expect this to be considered unethical. Withholding standard of care for a potential alternative might lead to death, so I can imagine this would remain in the animal phase for awhile. Regarding human subjects and not withholding standard of care, we are in a unique position. If curanderos deem n. lobota tea the standard of care in their region, and people are either resistant to trying or cannot afford the already available 1st world standard of care, I wouldn't consider it absolutely morally wrong to provide these people with, at bare minimum, a more effective preparation of something they are already taking and is not working in the long run. I would also like to note that reaching out to curanderos and getting them to cooperate is imperative to the study's success.
Curandero vs 1st World Standard of Care