Besides the Rosetta Stone, I don't know how either of these languages were completely translated, further both languages...well with Egyptian there were at least three ancient stages of development so I imagine the language evolved significantly in that time period. Pronunciations for modern languages sometimes change based on region and time period within 20 or 100 years.
With Mesopotamian, Babylonian, Sumerian, Akkadian, and Assyrian were all quite different, and I'm not sure which of them used Cuneiform, I don't understand how that was deciphered.
Most importantly, after seeing a post about how the Ancient Egyptian word for cat was Mau pronounced Meow I just find it hard to believe that we have any idea how these words were pronounced. Further, the Babylonian/Phoenician god Milqart, how do we know it's pronounced 'Milk-Cart' rather than 'Mel Cart'?
Have you checked out
Do we know what ancient languages actually sounded like?: On many ancient languages, including Egyptian and Akkadian.
Also, on how cuneiform languages were deciphered, we have this recent post:
To clarify on cuneiform languages: Sumerian is a language isolate but Assyrian and Babylonian are both dialects of the same language, Akkadian, which is in turn closely related to Hebrew and Arabic.