It's better to express your meanings by this :"他为什么不常常回山上的家里？" Even though there is no grammar mistakes in that sentence,we often don't use that kind of order to organise our words. people are not familar with that expression. Because If "the home" is the man's home ,it is a natural thing that he goes his own home ,so it seems more imitate to sue "回" than "到"。

There should be a 里 after 家, or else the sentence will be wrong.

对，没有不对的，中国的三岁的孩子可以与大人生活了，只要对方理会，怎么说都可以，中国的古代一天没有几句话，整天都是在用意之中，饮食很正常。

Your sentence is correct. Nothing wrong with it.

nothing wrong with this sentence :)