I agree that the HNWI certificate alone can not be used for DTT since it lacks the necessary information. Other documents would indeed be needed.
However, it certifies the person as a taxpayer (tax resident) in Georgia, so anyone having such a certificate should be able to request the initiation of the Mutual Agreement Procedure, in case of a potential dual residence (on top of other cases to be able to access treaty benefits).
The taxpayer may at︀ the basis of the International Agreement on the Avoidance of Double Taxation (DTA) ratified by︁ the Parliament of Georgia and in accordance with the “Rule for the Mutual Agreement Procedure︂ defined by the international agreement on the avoidance of double taxation" (rule), to request the︃ initiation of the Mutual Agreement Procedure (MAP).
The authorities can indeed refuse to initiate the︄ MAP, and in this case, they shall provide feedback within one month.
Let's assume you︅ are right in claiming that it can not be used.
In such a case, I'm︆ curious to know what they would provide as an answer.
Would it be something along︇ the lines of the following?
"Dear Sir,
Please note that the HNWI certificate is just︈ a paper with no legal meaning. It is just there to attract investments to Georgia.︉
Since you have stayed in Georgia for less than 183 days/year, we kindly hope you'll︊ consider that you've been wasting oxygen, which a mosquito could have used better. As such,︋ we'd encourage you to locate the nearest fire hydrant and attempt to fit it inside︌ your colon.
We remain at your disposal and look forward to hearing from you."
The sentence has to be interpreted in the light of its object and purpose, which is to exclude persons who are not subjected to comprehensive taxation︀ (full liability to tax) in a State, because it might otherwise exclude from the scope︁ of the DTA all residents of countries adopting a territorial principle in their taxation, a︂ result which is clearly not intended.