Joining the discussion having read most but not all so with that caveat....
Reiki practitioners do not ... or should not claim to cure ailments. Even in some quotations inserted by those supposedly saying reiki claims cure the wording in the quotation is aids healing . Please do read the wording before using a quotation.
We all have electrical "energy" in our bodies ... its how parts communicate with each other. Basic biology. It can be measured via machines. Just because most people cannot feel it does not mean it is not there. ... it does not make it woo if some people tune into it or alter brainwaves by meditation. We are all capable of slowing our own heartbeat if we try and maybe its a more tangible "proof" we can tune into and alter our awareness of our body capabilities if anyone wants to try. It would take more than a few minutes... it would take knowledge and concentration and practice. And maybe help from someone else. Just like someone wanting to tune into reiki.... and both can be a spirital journey or a practical journey.. for me it was practical , i needed to explore the science of it.
We use electromagnetic machines and ultrasound machines to view inside our body and also to assist healing with fractures and wounds. The important word is assist as the machine does not cure the fracture it stimulates the bodies own healing process to speed up the process . The clams made by Reiki associations claim only to do the same... to tune into those frequnecies generated primarily when a practitioners brain produces delta waves that resonate at low frequencies.
As to the non science bit.... well sort of as i dont know other than maybe science hasnt yet proven that all of us are connected on some frequency...
I was looking at a pic of a horse friend had put up asking for healing re a neck problem, cause unkown. During distance healing i got "feeling" of sudden pain in horses chest area when raising head. Told friend... week later horse been to vet and arthritis diagnosed by vet at base of neck ....which is in centre of chest in a horse.
i asked the owner of one dog i had no previous knowledge of what the issue was with the left shoulder as i felt cold... sometimes indicates scarring. She said none ... later she phoned to say previous owner told her dog broke that shoulder some years ago.
Only two examples where the placebo effect on human not involved or a human observation of the animal biased by belief or not.
Of course when engaging the services of any sort of practitioner one should not go blindly into that engagement... there are poor or greedy or unqualified practitioners that promise the earth in every aspect of life . . Look for the good ones that are willing to explain things and dont make extravegant claims.