Are clinical studies in less prominent foreign scientific journals more likely to be reliable than what is reported in major U.S. journals, due to less interloper interference with the studies or their interpretation?

Unfortunately, this is very much the case. While there should be accuracy and fairness across the board by scientific journals, given the level of scrutiny of author submissions by editors and high-level expert reviewers, at least ideally, the system is designed to have checks and balances to maintain quality and validity of the information provided. Unfortunately, as you have come to learn, there is much manipulation and corruption of all institutions, including the scientific enterprise, at all levels. That is a particular concern of the interlopers because they prize technology and believe it has the highest priority, and will work to minimize and control what humans can achieve. They will step in to throw a wrench in the works and contaminate a school of thought, or the work of opinion leaders and prominent investigators, to throw them off track, misguide them to go down the wrong path leading to a dead end and not a revelation that would bring a scientific advance and so on. Because the journals with the highest readership will have the greatest influence, oftentimes, the larger operations will be more heavily monitored and manipulated. That is why more obscure journals and journals from minor nations population-wise, as well as viewed as obscure academically, may well have incisive breakthrough-level investigations that reach the print stage, having gone through the normal hurdles of review, simply because they are not viewed as having a high level of influence in general, regardless of what they publish. It as a well-entrenched prejudice, in fact, that is further reinforced by the interlopers because it creates a level of efficiency for them. So they mostly need to worry about a relatively small number of leading journals in what they focus on, and can let the many smaller operations proceed on their own without handholding or being muzzled, thus representing less busywork for the extraterrestrial censors.