on the topic of meta-knowledge:
Sometimes the SI's simple presence can disrupt the 'canon' course. Sometimes from what the say/do even if they aren't trying to disrupt things.
Main Character A decides to visit with the SI, so they aren't at location B when event C happens, (which can be good or bad; maybe the MC misses a chance to meet someone important to the plot/find a Mcguffin, or maybe the villains are sitting around wondering why the hero hasn't walked into the ambush yet, he should have been there a half hour ago!)
alternatively something the SI says gives the MC a different perspective on things and they figure out a secret before they were 'supposed to' (accelerating the plot and possibly getting into a situation they aren't ready for yet)... or the MC gets the wrong idea and wastes time on a wild goose chase. Or the MC tries something that was technically possible but which they never would have thought of in canon.
in the Ring of Fire series (primarily) by Eric Flint, a 1990s West Virginia coal mining town finds itself abruptly in 'the Germanies' in November of 1631, smack in the middle of The Thirty Years War (both timeline wise and geographically) Simply being there sets off events which result in a year later people whom history said would be dead, and ones who should have lived longer being dead.
Some of the downtimers/locals upon learning uptime science/techniques combine it with their own know-how to create future developments 'early' and in some cases invent entirely new things.
Others make decisions (good and bad) based on info from the Uptime books and how they interpret it.
... I think I'm starting to wander away from the original point.
In summary, the SI's mere presence is going to alter things to some degree, maybe in ways that invalidate/change some of their meta-knowledge.
Sometimes the SI's simple presence can disrupt the 'canon' course. Sometimes from what the say/do even if they aren't trying to disrupt things.
Main Character A decides to visit with the SI, so they aren't at location B when event C happens, (which can be good or bad; maybe the MC misses a chance to meet someone important to the plot/find a Mcguffin, or maybe the villains are sitting around wondering why the hero hasn't walked into the ambush yet, he should have been there a half hour ago!)
alternatively something the SI says gives the MC a different perspective on things and they figure out a secret before they were 'supposed to' (accelerating the plot and possibly getting into a situation they aren't ready for yet)... or the MC gets the wrong idea and wastes time on a wild goose chase. Or the MC tries something that was technically possible but which they never would have thought of in canon.
in the Ring of Fire series (primarily) by Eric Flint, a 1990s West Virginia coal mining town finds itself abruptly in 'the Germanies' in November of 1631, smack in the middle of The Thirty Years War (both timeline wise and geographically) Simply being there sets off events which result in a year later people whom history said would be dead, and ones who should have lived longer being dead.
Some of the downtimers/locals upon learning uptime science/techniques combine it with their own know-how to create future developments 'early' and in some cases invent entirely new things.
Others make decisions (good and bad) based on info from the Uptime books and how they interpret it.
... I think I'm starting to wander away from the original point.
In summary, the SI's mere presence is going to alter things to some degree, maybe in ways that invalidate/change some of their meta-knowledge.