Proofread South Sudan Science Textbook (Grade 2-4)

We are from a Chinese publishing house. We've finished the first draft of the Scince textbook in English from Grade 2 to 4 and tailored to South Sudan. We now urgently need a South Sudanese (at least an African familiar with South Sudan) to help us proofread the textbook, to avoid anything that might annoy the students and teachers in South Sudan because of the misunderstanding due to cultural, religion and other reasons. We have 3 textbooks, each with about 10,000 English words, and each with a budget of 500 USD.