Since the Bible was completed in 98 C.E. would not the later definition of hell be invalid?

You can be a Bible lawyer all you want. The wicked have hell as their reward for wickedness.

The Bible wasn't completed in 98 CE... In fact Christianity wasn't recognized by Rome until 325 CE when Constantine the Great called together the First Council OF Nicaea. The Bible continued to be altered in 787 by the Second Council... a Total of 22 Catholic Councils were convened to alter the contents of the book right up to Vatican II in 1965

Er... well beyond the beginning of the 9thC before it got close to it`s present state.

The divinity of the Jesus chap was decided by vote, for example, only in 381 CE.

Some places where the English says 'hell' it is a translation of the Greek 'hades', which means 'the realm of departed spirits'. This realm contains both heaven and hell, as we think of them, but they are separated from each other. (Luke 16:19-31)

In other places it is a translation of the word 'gehenna', which means 'the valley of hinnom', which was the garbage dump outside Jerusalem in the days of Christ, where the fire never went out, and the worms never died. (Mark 9:43-48)

I don't interpret presence or absence in the Bible as indicating validity. It has all sorts of nonsensical s*** in it, starting with a talking snake and proceeding to things even less likely.