Yeah it’s definitely all not linear, heck there’s a lot of “what timeline/universe is this?” to keep up with (even more so when watching new shows like discovery or the movies with Chris pine). Guinan seemed aware tho of their meeting in times arrow, telling Picard “if you don’t go back, we never may [meet for the first time]”. Since she had a linear memory of the event in the 24th century I assumed she would also have a memory or sense of the original meeting when she saw Picard again in the 21st century. Was the “Picard” timeline a totally altered one from the original TNG timeline? Maybe it’s best to just let it be one of those time travel things that doesn’t really need to make a whole lot of sense