Good questions! So, something that would only require one pip is something like a violent and traumatizing murder committed with a knife. That would be a strong echo, and there would be no concrete time limit on how far back it could be sensed. Eventually that echo would fade, but it could be years or decades, and someone could read it with just one pip.
The two pip version is like Foresee, in that you can only get visions of events within one day of the present, just into the past instead of into the future . So using the same knife to chop wood is not really something that would create a strong echo, so you have to spend more pips to learn about that event, and have a time limit (which starts at one day) before that event is too far in the past to read.
Basically, events that are infused with strong or turbulent emotions or events that speak of powerful Destiny are strong resonances that can be read regardless of how long ago they were and with only one pip. Anything else requires two pips, and you have to try and sense it within a certain amount of time or else it’s too faded.
The Ages Past control just extends the time limit. You don’t read literally EVERYTHING that happened, but if you’re looking to sense what happened at a certain time, you can look back further. Does that make sense?
Like, with Foresee, normally you can see 1 event that will happen within 1 day. Wit the Duration upgrade, you can still only see 1 event, but it can happen 2 or more days in the future, based on how many Duration upgrades you have and activate. With Read, it’s the same. You see 1 event that was up to 1 day in the past. With Duration, it can be 2+ days in the past. With Ages Past, you still only see 1 event, but it can be 1 year in the past, and multiple additional years with Duration.
It’s basically Foresee, just in reverse, and you can go back further because it’s the past, so the GM doesn’t have to worry about making sure it happens the way you see it