there is no convention to write thai with these letters
compared to chinese whe have pinyin rules
you can write as you want
and in France we dont prononce the letters the same way than english or american
so we don t rite the same way
for exemple "dee" for a french is prononced "dey" for an american
so the best is to use thai letters :D
Sorry I have enoegh of Americans so I am full of claims 5555