hushed wadi
As the title says, make familiar quests more interesting. I'm sure many people are tired of seeing the "Do 25 stages with the character" and having to slog through every day just for player retention. My suggestion is this:
#1. Make the quests actually use the character the familiar is for.
Most of the time people don't even use the unit and just use another to kill everything while the familiar unit sits in tow, wasting away. Have them actually be placed and do something like Hollow Knight's Quest.
#2. Have better quest objectives
As I said previously, "Do 25 stages with the character" for 10 days (5 if you do it before the permanent quest) is a slog and definitely drives people away from the familiar. My proposal being things like, "Do X amount of damage with the character", "Kill X boss", or even "Use the character in X stage". This keeps people from repeating the same stage 25 times and actually puts some freshness in stage variety and activity variety.
#3. Player Retention is good but not needed
Yes I know Retention is good for you but forcing people to do the same thing 5-10 days straight (and yes some people take breaks in-between) is just outright ridiculous. A better way is just using #2 and removing the daily limit and having the currency be obtainable in a single day (or 2 if you really need those numbers up). This stops the slog and actually encourages people revisiting old stages and makes them use the unit the stage is meant for.
TL;DR
Change objectives to include a more active playstyle, using the character and stages they are meant for/came out with, while also removing the daily limit and having the quests be the unlocker not the currency like some of the anniversary units.
ember jungle
tall jewel
tight loom
placid hazel
but yeah it's rough
grave portal
worn crater