I believe that Eckankar was based on Paul Twitchell's logic and beliefs. It was what was logical him and what he decided must be true. It was not inspired by ancient wisdom in my opinion, because nowhere in no time in history do we have any proof of any ancient god or creature existing or speaking to someone.
Plagiarism was something Paul Twitchell was accused of concerning the belief system of Eckankar. Looking at the tenets of the faith it is easy to see it is a bunch of different religions patched together to create something new. Therefore saying that it was inspired by ancient wisdom is close to the truth. Saying it was plagiarized is probably the most accurate statement.
Eckankar is based on the Sikh religion. It only tosses away the notion that humans are the Gurus, and instead puts the faith in the religious text. Paul Twitchell is cited as the founder of the religion, but was only imparted with the knowledge through things that were already known, or taught to him. Very little does he claim as his own logic and beliefs. He simply interprets things a little different.
Eckankar is a spiritual philosophy and practice that has drawn a lot of followers to its meetings and activities. Yes, as often is the case, Paul Twitchell served as a catalyst for the movement; however, as is often the case, he is only bringing together a set of ancient wisdom teachings in a form he thinks will appeal to modern people.
No, I do not believe Eckankar to be based solely on Paul Twitchell's logic and beliefs, because he likely drew from a variety of inspirations, including ancient wisdom like he later claimed. Most people's belief systems, whether or not they become famous, are based on a variety of influences. Eckankar had ancient wisdom as well as Paul Twitchell's logic and beliefs.