As long as Mrs. Hawayo Takata was alive, Reiki history narrated by her was taken as true but after she died in 1980, many aspects have been questioned and are still being debated. Such points include the exact date of Dr. Usui’s meditation, whether or not he was a doctor and whether he learned from someone else etc. There is disagreement even on the count of master students taught by Dr. Usui and Dr. Chujiro. Similarly, whether or not Dr. Chujiro was a medical doctor, origin and use of Reiki symbols and so on.
Researching for facts is fine but if we look at it purely from practice point of view, history of Reiki doesn’t affect Reiki practice. One can practice even without knowing anything about the history. It is exactly like using various gadgets without knowing who, when and how someone invented the stuff. To be a good driver, one does not need to know who built the car. A person who is not concerned about the history but practices Reiki every day is far better than a person who knows all about the history but doesn’t practice or does it rarely.
I am not saying that one should totally ignore the history. What I am trying to say is that history doesn’t affect the Reiki practice. One can be a good Reiki healer without memorizing the history. You can carry out healing sessions as and when you wish and devote your energies to what is actually required, not to non-essentials.