You have to be confident that the source you are reading is authentic. If you doubt a particular website, then you cannot take their content as Hujjah.
However, there are many trusted websites that give you confidence that their books are authentic.
As for the translation, it’s Hujjah only if:
1- You are confident the one who translated it did so properly. He understands Arabic and translated it well
2- The source is trusted and so you can trust the reference
If you are not confident, you must refer to the actual source to verify it, or have a scholar verify for you. Otherwise it would not be Hujjah