Yes, of course. There are things we can answer with confidence about events last year that we cannot answer about events 100 years ago. In general, as we go back in time, it becomes harder to get specific answers. This is not always the case, however.
And the whole question is irrelevant. You suggested that the Earth was formed with an 'appearance of age'. That is precisely Last Thursdayism. Among other things, the Earth would have to be formed with radioactive elements, which decay at a variety of different rates, all set up in various strata to give the 'appearance' of increasing age with increasing depth. To get anything like consistency from all of these 'apparent' ages is exactly the issue with Last Thursdayism in a nutshell.
So, the difficulty of reconstruction in detail is *far* from not knowing anything about the past. We can, and do, use the remnants of the past as clues to what happened in the past. While we might now know all the details, this is often enough to give general answers.