The solution to your comments boil down to dedication in learning about a tradition or, at least, to know its foundations. Much of what you are relating in your post concerning Advaita refers to what is commonly called neo advaita today. This modern pseudo movement is a travesty of Vedanta, as well as many other modern so-called traditional expressions of traditional Vedanta today.
The tendency to syncretize Advaita with Buddhism is also common to many other religions and traditions (like ‘Christ Consciousness’ for example tries to meld Hinduism with Christianity). The resulting eclecticism(s) would seem to stem from a poor knowledge of the origins of each distinct tradition and a certain desire to reject or even revolt against traditional or institutionalized religions. This is understandable to a certain extent – as the institutionalization of most religions have resulted in veering far from its initial motivations – and yet the desire to separate spirituality from religion has often resulted in such eclectic and confused views. Neo advaita is a prime example.
Moreover, proper translation is an important factor when considering any author or founder of a tradition. Nisargadatta, coming from the Nath tradition, has been widely mistranslated from Marathi to English. I once read and studied all his books (even his teachers’ books) for years but remained relatively confused. To give but one prominent example, many of his translated books (into English) regularly add confusion by separating words like consciousness and awareness. The reader is often left in limbo as to what he was really driving at. As a result, many neo advaitins instrumentalized these confusions to syncretize their newfangled interpretations.
This is another factor that we have to consider when we try to assess the credibility of any teaching, and it applies not only to the teachings of Sri Ramana but also to the teachings of all other sages or gurus , including both those who have truly merged and lost their finite sense of individuality in the non-dual and absolute state of atma-jnana or true self-knowledge, and those who are merely reputed to have attained that state. For example there are many books in English that supposedly contain records of the oral teachings of Sri Nisargadatta Maharaj, the other guru whom Innerself mentions in his comment, but Sri Nisargadatta actually spoke only or mostly in Marathi, so most of the records of his teachings are not in his own words but are only translations of them.
I have seen some quotations in English of what Sri Nisargadatta is supposed to have said in Marathi, and I have glanced through some of the English books that are supposed to contain records of his teachings, and frankly I found that there are many confusing and questionable ideas expressed in statements that are attributed to him. However, since I do not know how accurately such English recordings of his teachings reflect what he actually said in Marathi, and how clearly the people who translated or recorded his oral teachings understood the real meaning of what he said, based on such English recordings I cannot judge how credible his teachings really are.
However, to be fair to the teachings of Sri Nisargadatta, I must admit that what I observed in the English recordings of them is equally true of some of the English translations and recordings of the teachings of Sri Ramana. Unfortunately many of the available English translations and recordings of the teachings of Sri Ramana lack clarity and accuracy, and hence they sometimes appear to convey ideas that are confusing and questionable, and that taken in isolation could therefore raise a doubt about the credibility of his teachings. Therefore I do not think that Innerself is entirely correct in his belief that “… one can trustfully read their books and/or written answers published”.
Since many gurus who have now left their physical body did not actually write any of their teachings but only expressed them orally, we unfortunately do not have any reliable source with which we can compare and judge the accuracy of the available records of them. However, in the case of the teachings of Sri Ramana, we are fortunate that he himself wrote his most essential teachings in clear Tamil poetry and prose. Therefore, though some of the translations and recordings of the teachings of Sri Ramana may not be clear and accurate, we do not have to rely upon such translations and recordings in order to understand the true import of his teachings, because a perfectly clear and accurate record of his teachings exists in his own writings.