Answer
Regarding an authentic version of Hari-bhakti-vilasa, even if you obtain the original text, it is not easy to understand simply by reading it on your own.
In fact, with devotional scriptures, there is a greater possibility of misunderstanding than understanding if one reads without proper guidance. The reason is that scriptures must be explained by an acharya. Shastra is meant to be understood through the teachings and commentaries of realized spiritual masters.
Therefore, unless you have a translation and commentary on Hari-bhakti-vilasa written by a bona fide acharya in a way that is understandable for people of our time, it will be difficult to properly grasp its teachings.
Consider the example of Srila Prabhupada. He translated and commented on many scriptures in such a way that people in the modern age can understand their true message. Through his books, we can understand the Bhagavad-gita, Srimad-Bhagavatam, and the teachings of Sri Chaitanya Mahaprabhu as they are meant to be understood.
Since we do not have a widely accepted commentary on Hari-bhakti-vilasa by an acharya specifically intended for us, it is not advisable to independently study that text with the expectation of fully understanding it.
On the other hand, whatever instructions from Hari-bhakti-vilasa are relevant for our spiritual practice have already been explained by Srila Prabhupada throughout his books and purports. The essential teachings required for devotional service are available there.
Therefore, by reading Srila Prabhupada's books, following his instructions, and sincerely practicing devotional service, the purpose of Hari-bhakti-vilasa is effectively fulfilled. The goal is not merely to read a particular scripture but to understand and apply its teachings so that we can advance in Krishna consciousness and ultimately return to Krishna.
Even if an authentic edition of Hari-bhakti-vilasa becomes available, understanding it properly would still require the guidance of an acharya. Translation alone is not enough; the correct understanding must also be given.
In The Nectar of Devotion, Srila Prabhupada discusses the principles of vaidhi-bhakti and explains that there are sixty-four items of devotional service. Among his instructions is the caution not to read too many books indiscriminately. Why? Because one may become confused, misunderstand important points, or receive explanations from unauthorized sources and thus develop incorrect conclusions.
Sometimes devotees think, "I will read all the scriptures. I will study every available book." However, the scriptures themselves address this issue.
In the First Canto, First Chapter, Eleventh Verse of Srimad-Bhagavatam, the sages of Naimisharanya ask Suta Gosvami:
"There are many varieties of scriptures, and in all of them there are many prescribed duties which can be learned only after years of study in their various divisions. Therefore, O sage, please select the essence of all these scriptures and explain it for the benefit of all living beings, so that their hearts may become fully satisfied."
The sages recognized that there are countless scriptures and innumerable subjects to study. Properly studying them requires guidance and many years of effort. Therefore, they requested the essence.
That essence is Srimad-Bhagavatam.
If one sincerely studies Srimad-Bhagavatam under proper guidance, there is no need to separately study every other scripture. This is one reason why Srila Prabhupada took such great care to translate and write extensive purports to Srimad-Bhagavatam. It contains everything essential for spiritual practice, spiritual advancement, and the resolution of spiritual questions.
Therefore, rather than searching for an authentic version of Hari-bhakti-vilasa or many other scriptures, it is better to deeply study the books that have already been translated, commented upon, and thoroughly explained by Srila Prabhupada. By doing so, one receives the essential teachings necessary for successful advancement in devotional service.