So do you think that the Cave of the Past actually holds any kind of time travelling powers itself or where they only able to travel back thanks to the Zodiac sword? Why did the sword throw them into the past anyway? And what was the point of going back in time to the village of the hidden rune? Was it just a cheap way to show you how Ted got his rune?
...And why, if you dont need the Zodiac swords power wouldnt some bad dude slaughter the monks, go back in time and rule the Suikoworld via manipulating events of the past? Sorry I do realize that ive left about five questions in one here.
Answering your questions in order:
1. I suppose it has some time powers, the name kind of implies that "cave of the past"
2. The sword sent them back in time, probably, just because the game needed a way to show you ted's past, give more reasons to hate and make windy, yuber, and neclord more evil. mostly it was just story arc tie-ins, and the sword was merely a plot device to that end. (When Konami 1st made the Zodiac sword in S1, I doubt they knew how far they'd develop it in later installments).
3. same answer as 2 really
4. For the most part
5. The past seemed to be to some extent immutable in the suikoverse. Tir and Co, were their to observe events more than anything. Remember nothing changed because of their appearance, The village was still toasted, ted's Grandpa still died, and the biggest hint of unchangeable past events in ted couldn't come with them back the present.
So even if some bad guy could go back in time, I am not sure if "Destiny" "fate" or " the will of the 27 Runes" would let past be changed. Even if the bad guy could change things, i am sure some rune somewhere, and some hero somewhere would show up and set things right.
tangent over, lets stay on topic.