I can agree with the supposition that there may be a pre-inclined disposition of say an Fe dominant individual to objectively evaluate what their motivations are through extroverted feeling - but what the motivation by itself would be cannot be determined through thought processes.
In other words, you can type a person in JCF as a particular type based on what their thought processes are, but not based on what their motivations are.
The realm of motivation is Enneagram and social behaviour is instincts -- especially with regards to wanting to fit in and belonging ... It's just much better explained there than Jung or Meyers ever did.
However, the core difference also is that Enneagrams are very much a psycho-spiritual system as opposed to pure psychology - which is what Jung is. MBTI and Kiersey however, is Pop Culture psychology in my opinion and using them in conjunction with JCF is detrimental to typing methodology. If one wants to analyse themselves purely, then they need to study Jung with the knowledge that MBTI and Kiersey are based off of his work.
They all want to talk about the same thing - but they're not all completely accurate. By putting it all together into 1 system, you may have a relatively complete psychological profile of an individual.