These changes look OK on paper, but leave quite a bit to be desired. AI-based abilities in Warframe are always iffy to use, and Nyx's 1 receiving better pathing as well as the damage increase seems promising, but we'll see how good it is in practice. An armor debuff is welcome, but the Infestation thing seems very niche and situational, not sure I like it. Nyx's 3 paired with her new passive seems to be okay, but it looks to me like a much watered down Nekros Terrify for CC purposes, and enemies *still* can shoot you and harm you regardless, it's just slightly more insurance. Additionally, I was under the impression that the math of Absorb would be changed? All that was added is dynamic damage output similar to Zephyr's 4, which is a step in the right direction, but even so her 4 was never a good ability to use unless you use the augment and use it to revive allies to gain temporary godmode. Releasing her 4 would just knock down enemies as opposed to killing them still, and you can still get easily killed in that downtime regardless, so it seems counter intuitive to me.
Meanwhile for Titania, she needs a better AoE range on her Spellbind, better buffs overall for her 2 that don't make her so situational, and better survivability on her 4. Also, maybe make it so that we can shoot the lantern and then explode it, similar to how we can shoot Nyx's mind control target? That'd make for a very great offensive use of her Lantern.
These changes are a step in the right direction, but still leave quite a bit to be desired, and I'm not so sure that these two lovely frames will budge much, if at all, from their current spot.