Theoretically true, although the points I raised about the gospel attributed to John remain. Now the original of the gospel attributed to Mark is purported to have been from about 70CE, so that's slightly nearer in time compared to the gospel attributed to John. But we are still 40 years after the purported events. But the geography is more challenging - the gospel attributed to Mark is considered likely to have been written in Rome, which is even further from where these claimed eye witnesses would have been. And the issue of language remains - the language spoken by the early readers and the language spoken by the purported eye witnesses is different.
But there is a further issue - we have no idea whether the text in Mark 10 was even present in any early version - we don't have early extant copies for most of the gospel attributed to Mark, indeed for much of it the earliest copies we can actually consider (and therefore be confident about the text) are from about 300 years after the purported events. And we know that there is evidence of significant alteration in the text - including the humdinger of a completely new ending added to 'beef-up' the resurrection claim.
But even if we accept the theoretical possibility that an early reader could have travelled half way across the Mediterranean to interview the purported eye witnesses - do you have any evidence that they did. Seems to me these are faith claims, and accepted/rejected on the basis of faith, not on the basis of evidence.
And that leads me to my final point - if there were all these eye witnesses to astonishing miracles, how come christianity failed to get any meaningful foothold in the place where it arose (where those eye witnesses actually lived). Those most likely to have been witnesses to Jesus' life and teaching by and large did not accept that he was anything special, did not accept him to be the son of god, did not join the developing christian movement. Weird if they were witnesses to astonishing miracles!
Thank you for acknowledging that it is theoretically true that someone could have checked whether Bartimaeus had been healed. As you know, I think that eyewitnesses were still alive when the four gospels were written.
For example, Paul says "After that, he appeared to more than five hundred of the brothers and sisters at the same time,
most of whom are still living, though some have fallen asleep." Presumably these 500 had also witnessed other miracles.
Also, Luke says that his (and other composers of an account of the events) information comes from "those who were eyewitnesses":
"Many have undertaken to compose an account of the things that have been fulfilled among us, 2just as they were handed down to us by the initial eyewitnesses and servants of the word."
Regarding your final point.
John 9:18 says "The Jews still did not believe that the man had been blind and had received his sight
until they summoned his parents 19and asked, “Is this your son, the one you say was born blind? So how is it that he can now see?”" Notice the "until", indicating that they did eventually believe he had been healed, once they had spoken to his parents. They then spoke to the man again, eventually telling him, "we know that this man (Jesus) is a sinner...We know that God spoke to Moses, but we do not know where this man is from."
So as we are also told in the Synoptic gospels, and indeed one or two other secular writers from that era, the Jews did believe that Jesus performed miracles, but did not believe that the source of his power was God.
