Okay alot of folks don't really get the implications of the Star Trek cosmology, with its endless time travel & mutual incursion from other universes.
Is there a paradox about when the Eugenics war occurred? Yep, and their should be, because with all the time travel and temporal shield and weird pheonoma and pockets of time that moves at different speeds, the "Prime Universe" should be filled with anchronisms and weird contradictions.
Even La'an is part anchronism now, she has memories of events that no longer happened, yet events that don't exist shaped her. She breathed the air of an alternate timeline and absorbed is light through her skin to produce vitaman D, microscopic bits of that timeline are still in her as she interacted with it. This changes the amount of energy and matter in both universes.
And I haven't even got to the effect her act of time travel had on future time travellers, who then go back in time and shape her past and future, which then changes her trip and that in turn changes the future acts of time travel in an endless cycle of time travel and transformation.
Also Kirks dead body still exists in the past, buried somewhere or cremated ashes, a lingering anchonism.
And this actually explains all the contradictions in Star Trek, from how the Defiant's size varying by huge amounts for example.
It also means that when La'an went into the past that moment was both her past, present, and future at the same time.
Look up a setting called Mage: The Awakening thatexplores these themes.