How much evidence is there of long-term effects of these types of treatments? Do you or other researchers in the space ever worry that you are in a sense curing

How much evidence is there of long-term effects of these types of treatments? Do you or other researchers in the space ever worry that you are in a sense curing the effect and not the cause (family and societal problems as I understand it), which would imply that efficacy would fall over time? Would sustained fecal transplants, etc. even work?