Sorry, but although this seems to be correct grammatically (although a comma after commentary would be useful), it doesn't really make sense. The meaning is unclear. "extend the annotation with the commentary" "add a commentary to the annotation" might be better. "contradicts the idea of interpreting oneself (or by oneself)." I can't really help you here as I don't know what you mean. "interpreting oneself" and "interpreting by oneself" have different meanings. I think you mean "by oneself" as you are interpreting the material, not yourself. Think of another phrase for "contradicts the idea" Maybe "defeats the object of interpreting it by oneself."

contradict. As the translators is a plural.

Sorry, I thought I'd posted that as an answer. Sorry, but although this seems to be correct grammatically (although a comma after commentary would be useful), it doesn't really make sense. The meaning is unclear. "extend the annotation with the commentary" "add a commentary to the annotation" might be better. "contradicts the idea of interpreting oneself (or by oneself)." I can't really help you here as I don't know what you mean. "interpreting oneself" and "interpreting by oneself" have different meanings. I think you mean "by oneself" as you are interpreting the material, not yourself. Think of another phrase for "contradicts the idea" Maybe "defeats the object of interpreting it by oneself."

The translators opted to extend on the annotation with a commentary that contradicts the interpretation (of it) done by himself.