Here are some suggestions I've come across:

1) As I said in a comment on the main mod page, I feel the balance of the traits (namely, fertility being too harsh too quickly and lifespan being too long (despite lore)) are less than ideal; however, that's something to just tweak over time.

2) I found that, with my combination of mods, I saw too many heavenly roots. I made the following on_actions file to address this:
with the two handle_x_roots_reinforcement removing the root, then having a chance to add it or a lesser root back based on parent's roots; the values of which I'll leave up to you if you feel this is a good idea.

(Edits: Fixed formatting)

too many heavenly roots? opposite for me, my game its almost half of population had poor roots

it's probably because I happened to go blood legacy track, so my dynasty kept getting them; but also, I'm probably wanting much rarer roots than I was seeing, and now have like a dozen heavenly roots alive, tops, at a time. I guess a gamerule that controls rarity would be my recommendation

powerful talents generate kids with also powerful talent, i think the heavenly trait should just add -50% fertility and that'd fix the issue

@Thot Smasher 69 true, despite the lore its gamebreaking if everyone just have heavenly roots lmao

I have noticed that the roots I see are either Heavenly, Normal, or Poor, with the two mid-grades almost not naturally spawning! Definitely feels a bit off, but I assume things will balance out as bloodlines develop. My main guy is still only a core formation expert, so he only has a few dozen children. Can't wait to get a massive dynasty going with talents all across the lands!

OH! I know! Add in memories! Break through's would be momentous occasions in a character's personal life, so those should be marked in memories! For example, when a character finally reaches Nascent Soul, it would be narratively correct for them to reflect back on their lives and the moments surrounding their previous breakthrough points. Plus, it's just cool to see how fast some characters break through compared to others, especially if a MC type cultivator shows up as a Nascent Soul at 30, for example!

interesting take

Prowess bonuses should be way higher. Foundation Establishment giving less prowess than a weapon artifact ain't it. Foundation Establishment should be at least 100 prowess. I'd suggest starting off at 5/10 prowess and then doubling the prowess after every breakthrough.

Maybe events that give permanent buffs or a lifestyle tree?