Obviously, the further back in time you go, the less certain we can be of the accuracy around the dating of events and individuals. The history of Ancient Egypt is a classic example where we have the Low, Middle, and High Chronologies which present the dating of the same set of events using three different sets of dates.

Even though the Low Chronology is often considered the mainstream view and is backed up to a degree with astronomical data, and archaeological evidence, there is still no consensus.

When you add religious and theological considerations into the mix as is the case, for example, with dating events from the Tanakh/Old Testament, then the complexities multiply.

As for the decisions I've made when placing events with debated dates in the Timeline, in the large majority of cases, I have come down on the side of the mainstream consensus viewpoint and in some instances, either made a note to the effect that there are other possible dates proposed by some scholars, or actually included the event twice (as is the case, for example, with the birth date of the Buddha in the section on Buddhist history).

While this approach may not keep everyone happy, the Timeline is actually editable, so anyone with a greater specialist knowledge of a subject can make amendments to it where they see fit to do so. And hopefully let me know so I can make a correction where appropriate!