1) Fern said to her mother - не "said to", a "asked".
2) ax - такого слова нет, зато есть слово "axe".
3) to kill is a runt pig - "is" - лишнее.
4) A girl of eight years - правильнее будет написать "A eight years old girl".
5) seared - может быть "scared"?
6) ran for his father - "girl" - женский род, а потому не "his", a "her".
7) Fern said to not kill it, please - "please" - лишнее.
8) would have - правильно использовать "had" (без "would").
9) said she went back to the house - 1) "said that she went". 2) "back into the house".
10) and he would bring the runt - "and that he would...".
11) Arable pig brought into the house, he was a newborn and white - "When Arable brought the pig into the house, it was newborn and white".
12) The father said he than belongs to Fern - "The father said that it belongs to Fern".
13) Girl - "The girl".
14) She looked at him and said that he was perfect - "She looked at it and said that it was perfect".