Both of those feature heavily in my big rewrite. The Second Great Schism came about when some Jedi were conducting experiments into influencing midi-chlorians to alter the natural growth cycle of living things. Later, this would be taken further to impel these microscopic Force-conduits to spontaneously generate whole life forms from nothing. But the Jedi Order reacted by forbidding the experiements. Then, when they didn't stop, exiling them ('cause
that'll make 'em stop
). A fear response. When the Sith came on the galactic scene, it was because of those exiled Jedi. Once the Order realized this, they got even more afraid of the Dark Side --all the while no doubt protesting they weren't. The detachment of the Order we saw in the Prequels was the ultimate extent of that -- rejection of emotion to an unbalanced, unhealthy extreme.
I have a bit more nuance in my take on things, including, as I'd mentioned previously, tensions between the Jedi who are out in the galaxy versus those sitting in their high tower. I have Obi-Wan discover that dark secret from the Order's past, the revelation that the last age of the Republic, millennia of war, the rise and fall of the Mandalorians, the existence of the Sith... It's all the Jedi's fault and they haven't told anyone out of a festering sense of guilt. Which feeds the Dark Side. What you refuse to look at or know within yourself has power over you. The Jedi are effective when acting out of
compassion, not passion, and not dispassion. The Jedi and Sith of the film era are like an off-balance washing maching knocking itself to pieces.
The Jedi grail is giving without overgiving, involved without being attached, optimism that is not panglossianism... Constant mindfulness of individual motive. Don't try to control others. Don't see yourself as "better" just because you can do a thing most can't. Power corrupts -- but has less opportunity to do so if one has been conditioned most of one's life to this kind of constant... well, basically Dialectic Behavior Therapy. *lol* I would be a burden for some. Corruption is a part of nature, too, as Rey saw under Luke's guidance in TLJ. It just needs to be in balance with everything else. The "temptation" of the Dark Side is that over-reliance on the easier thing throws the whole out of balance. Fear and anger are healthy and natural -- but when one is unaware that's what one is feeling, or in denial about it, it skews to unnatural extent that drowns out the other stuff.
As I've said before, the problem wasn't that the Sith used the Dark Side -- the problem was that they
wallowed in it, rubbed the Jedi's noses in it, flaunted it. And the Jedi... Well, there's an old aphorism: "What you resist persists." It's part of the underlying principles of Tai Chi and Aikido. The harder you push against a rock, the harder that rock "pushes" back. Meeting force with force just means ever escalating force on both sides. The Jedi were blinded by fear and guilt, and pushed back against the Sith over and over and over. Never occurred to them, in their fear, to
go with it. Stop resisting and, in finding their own balance again, let the Sith use
their imbalance against themselves. That could
almost have been the point when Darth Bane came along. The Sith were well on the way to wiping themselves out when he created balance in them, of a sort.
But I have stuff later on -- in my own version of the Sequel era -- where, rather than magic vague "Force-healing", I have a couple very specific instances. One where a Force-user exhausts himself channeling the Force to speed up someone's natural healing mechanisms to keep what would have been a fatal wound from being so... But also once where someone uses Force Lightning to jolt someone else's heart back into rhythm, like a defibrillator. Showing what balanced use of abilities looks like once you look into the places you previously dared not look.