So, it sounds like the book of Asher is about as authentic as the rest of the Bible. Consider the similarities:
But the book in its entirety cannot be so old as shown by chapter 10 covering the descendants of Noah which even contains medieval names for territories and countries,
Most of the books of the Bible are not as old as they claim, nor were they written by the person who claimed to have written them. Daniel comes to mind. As for using the wrong names, Moses likewise refers to the city of "Dan" which was not founded until long after his death.
Most of its extra-Biblical accounts are found in nearly the same form in either other medieval compilations, or in the Talmud or in other midrash or in Arabic sources.
This is common in the Bible, as well. Some stories in the Bible are reworkings of myths from other cultures, and some parts are directly copied from other non-Hebrew writings.
For example it contains the common tale that Lamech and his son Jabal accidentally killed Cain, thus requiting his wickedness for slaying Abel.
The book of Jude takes quotes from some rather silly apocalyptic writings, such as the book of Enoch. The Bible also seems to think that the Nephilim continued to exist long after the flood.
So, in other words, I agree with you. The book of Asher is full of crap - just like the rest of the Bible.
In the case of Jochebed, the writer clearly got mixed up, crediting Moses mother with being the daughter of Levi. Since Levi was a grown man with several children, and the Bible gives his age at death, we can calculate a possible range for Jochebed's birth date. Then, give the Hebrews enough time to multiply from 70 to 2 million, and Jochebed now has a child. The writer clearly messed up. However, that shouldn't surprise us. The entire exodus account is likely fiction anyway.