I asked the question Why does Spanish have different names for the letters of the alphabet from English? on May 13 and I have received a number of comments as well as some answers. However, my question has been downvoted to -1. I don't know why I have got that downvote?
I don't know, but I can conjecture. The question is incoherent. You ask why the letters can't be given universal names for all the Latin languages, but you also ask why the consonants have different names in Spanish compared to English. English is not a "Latin language", so English is completely irrelevant given questions on the table. The question that you end with has a presupposition that is false. We can give universal names for all letters in all languages, if we have a sufficiently dictatorial government who can impose a standard and penalize transgressors. Question of the kind "why can we..." are always terrible, in the context of a fact-based venue of inquiry.
The question of why Spanish and English have different names for letters seems to presuppose that they should have the same name, and you are wondering why your presupposition is false. Why is your presupposition reasonable? It is such a common-place experience that languages differ in what words they use for X that you should expect the words to be different, and perhaps only surprised when they are the same. I wonder if you were even aware of the presuppositions contained in your question, that is, you didn't think about what you were asking and you didn't try to answer your own question.