"It's still not clear to me, however, whether our failure...."
No, it is unclear to me as well, but sod the Mulberry Bush and its supporters, you do, as I do, keep trying to reach a point of understood agreement about whether we disagree or not.
Now, in the second sentence second para, why say "defines" a particular time? It is the physically existent state which exists, time is a measurement system. And the definition of what did so can only be established as at any given point in time (a "particular time"). So, yes, we have particular time, particular existent state (incidentally, this is in respect of anything, could be the universe, or a ball, or you). The expression is sort of correct, but the 'wrong' way round. A point in time (ie a unit, as in timing) is, by definition, definable by the quickest at which any given alteration occurs. But, as it is a measuring system, any reference will suffice, just the more frequent and constant the change, the better.
I then worry about the phrase before that: "A particular configuration...of the physically existent reality". There is no 'of something', there is only a physically existent state as at any given point in time. Nothing else. The previous state has been superseded. And if there is any form of change, then it must be a different physically existent state (that is what different is). There can only be one at a time, ie there is no change/alteration within any given reality (which is a shorter word for physically existent state). Our problem is that we are conceptualising reality from a higher level (never quite sure whether less detailed equals higher), so we latch on to certain superficial physical characteristics, and unless they alter, deem it as being the same thing, an 'it', albeit perhaps altering in some respects. This is incorrect. There is, in reality, a sequence of different 'its', they just have similar characteristics at a very superficial level. There is no 'leaf', as such. There is a particular physically existent state, then another, and another, and so on. A property of the 'stuff' (technical word!) which comprises any given state causes alteration. Now, during that sequence of change, 'it', after being a 'bud' resembles what is known as 'leaf'. Eventually, as change continues to occur, having altered in colour, texture, shape, etc, it disconnects from the tree (or Mulberry Bush, even), but we still refer to the subsequent existent states as 'leaf'. Finally it is no longer constituted in a way which gives it the characteristics of 'leaf'. But in physical terms, there never was an 'it' ('leaf'), there was just a sequence of different physically existent states.