More than just translating words a good translation will capture the meaning of a sentence then closely transmit this meaning to the target language. It also needs to be readable. Does it flow and engage the reader. While this should be true of the original text it continues to hold for the translation. And for this you need to understand who is your target audience.
A correct understanding of the original. If handwritten is it clear? Which language and dialect are you using, make this clear. Any cultural pitfalls to be aware of? Will the text expand to accomodate more words to explain the original meaning? How will this fit into the design? Then have you considered the right font for the language? Does it handle all the characters, accents and other special features?