As per instructions in the guide I agree with Lahoree, you need to certify everything that is a copy of the original (english or not) since you need to prove that the copy is a true copy of the original document (that only can be done by a notary or other authority mention in the guide) this are copies like: copy of passport, copy of birth certificate, copy of marriage certificate, copy of national ID of your country of current residence, etc..
You don't need the certification of the translation done by a notary, about the translation you need the certification provided by the institution who regulates the translators and makes them public authorized translators, this can be different per each country so I can't say what exactly you need in your country.
And if it helps, the guide specify very clear that you DON'T have to provide any original document of anything, only a few documents would be originals such as IELTS and police certificates. I hope you are not providing all the originals of documents mentioned above, these are unique documents you should not provide to anyone.
I know it is hard but if you think logically, it has a reason. Yes, it is costly and hard work... but I guess all of here knows this is not an easy task.
Hopes I help with my explanation.
