Could there be a reason why doctors Pregabalin and gabapentin very often in the UNBUFFERED Cetomacrogol cream prescribe I. P. V in the buffered?

In The answer to the question you refer to, the emphasis is placed on stability. Both molecules are amphottar and resorption does not seem to be evident. The isoelectric point of the two Moleclen situates itself around pH = 7. Given that the compounds are electrically neutral, a pH = 7 may be appropriate for proper absorption.   How easy or difficult one can set a buffered Ceomacrogol cream to pH = 7 with e.g. NaHCO3, I don't know. In an answer to an earlier question, this was recommended.

With an unbuffered Cetomacrogol cream you do not have the pH of the buffered. I do not know the pH of the unbuffered. But she situates herself around 7 then we are good. If not then one can try with small amounts NAHCO3 set them to 7.  

If you look up the formulary that belongs to the Unguator on the website of Qualenica under pharmaceutical preparation, you will find a simple modus operandi to prepare Cetomacrogol cream.