These days there’s a fair amount of published research about, not specifically 5
Elements, but about the effects of some of the modalities based on the 5
Elements, like acupuncture, Chinese Medicine– and even meditation. There’s also a lot of research about the effect of relaxation on the system, the effects of stress on the system and so on. You could do a Google “scholar” search for the research– scholar can be found on the main page of Google, at the top under thetab marked “more”. There’s a drop down menu there with scholar towards the bottom of it.
Only you can really decide whether you’re getting good value from a practitioner or teacher. But questions you can ask first include: How long has this person been practicing? Do they have a recognized qualification? Can I talk to anyone who has been to this practitioner? Do they have any social proof?
The main thing is that you get along with the practitioner and that they are honest about whether or not they can help you. If you have any doubts about them, then move on.