[yorwba]

> old scientists wrote in books how to read each letter and its rules. It is written in detail where each letter will come out of the mouth and what features(like the sibilants, the stressed letters, the soft letters, the labiolinguals, and tremolo etc. ) it will have

Indeed, that is why modern scientists believe that ﺽ must have represented some kind of lateral sound, like a lateral fricative (or maybe a lateral affricate or a stop with lateral release – the descriptions aren't detailed enough to distinguish between these options.) But most modern speakers nonetheless pronounce it as a plain stop or dental fricative instead of lateral.

Having a description of the pronunciation doesn't mean that someone reading the description will be able to follow it perfectly. Otherwise everyone learning a foreign language would be able to develop a native-like accent just by reading about the correct pronunciation.