ok since you messed up now it's 6-7 missing instead of 12 missing. 
What did I mess up? There are 6 additional letters added to the caligraphy from the South Arabian script, as well as six more letters which are not officially part of the modern alphabet, but are nonetheless used as if they were a part of the Quran, such as Ta Marbuta, or Aleph Maksura:
In addition to six
ADDITIONAL SOUNDS there are :
1. Hamzah - was not available until 8-9th century;
2. Ta Marbuta ة - likewise;
and several more, albeit I do not remember to see Vah ﭪ for example in the Qur'an, but hamza and marbuta are frequent.
Even six additional sounds were not a part of Nabathean script, from which the Quran stems, not to mention six more additional letters.
Don't make silly conclusions if you do not understand what I am talking about in the first place.
Besides I am still waiting for a response to my previous question. If it is written in Arabic as you claim, why is it there are hundreds of foreign words which require special sounds? It's a third time I am asking this.
they didn't stop counting at 400 knew their language no need to dot some letters in script e.g.
900 ظ ẓā which is a completely different sound from 9 ط ṭā
Do you sinserely believe that is a convincing explanation? I guess this explanation helps you sleep well at night with your "translation".
Likewise clearly visible in Birmingham manuscript dated 568-645 CE numerous dot examples.
Occasional constonants added, in the context of what I said previously it does not matter. Occasional vowelizing in those horrible copies clearly looks as if they did not know what to do OR it was a schooling copy, which was meant to be washed over and over again.
In fact, ختم for instance, does not require خ and can be simply written as حتم with the same meaning of seal, mark, limit in most Semitic dialects, such as Hebrew חתם.