Hello, I am Vietnamese people.
In my language, the old principles of major system don’t work ( 1 = t, 2 =n, …) well.
So, I want to create new principles for Vietnamese.
Here is my short study . You can download by this link.
I get what you were trying to do with your analysis. Bear in mind though that the Major System isn’t actually for the Latin alphabet but reflects the frequency of those consonants in the English language. You’ll find people changing some of the consonants for Spanish, French, German, etc because they face similar problems you do.
However given that Vietnamese is a tonal language, I’d suggest you check out rhyming systems used by Chinese competitors. Also this here might be interesting (not the solution) but goes to show that the Major System has it’s limitations across various languages:
You could also just set up 00-99 in English and after you start to have a decent idea of which number is which word, meaning a direct number to image translation (not going via consonants), replace the English words with their Vietnamese translations. Once you’ve trained your system you’ll think in pictures anyways, so it doesn’t matter.