I cannot find anywhere that has a phonetic definition of the numbers.
Some, though not all, of the Sumerian numbers are known from syllabic spellings. There is an overview here
Sumerian has been a dead language for nearly 4,000 years, and had no known linguistic descendants, predecessors, or relatives.
Its printed form was logographic, which means each word was represented by a symbol. So there's no phonological content to be gleaned from their writing either.
So we don't know for sure how any of it was pronounced.
I don't get the comment about how would you pronounce ancient sumerian? In English. That's not really a helpful answer.
Know it's already been linked, but this one explains the numbers and how they're cognate of other numbers. I think that's the reason it looks like some numbers are missing on lists.
The Language Gulper: Sumerian Language