I guess there's some of curio that are really out of the schema, like volva's wand(which is 3 slots for like 230 lp/hour q10).
My opinions about curios that I know:
Volva's wand -> reduce from 3 slots to 2 or increase it's value on q10 from 3000 to 5 000 lp/hour;
ratte-tattle-talisman -> reduce slots from 2 to 1 or increase it from 4500 LP to 6750;
Seer's tea leaves -> increase from 1200 to 1800 lp;
Dark effigy -> increase duration from 11h 23m to 32 hours and increase the LP from 2 000 to 6 000;
Crabshell sunfeather -> Decrease from 54 hours to 36 hours ( since crabs do wound most of time it would be a fair price for the wounds);
Nine-tails -> Put another product( dreams or string) on the recipe or make squirels able to tame;
Oak spire -> Increase the time from 45 hours to 60 hours and increase LP from 4 000 to 8 000;
Primitive doll -> Increase LP from 850 to 1 200;
Cornucopia -> Increase LP from 5 000 to 10 000;
Horrible knot -> Increase learning points from 750 to 1 000 OR decrease it's time to 10 hours ( rather stick with time reduction, because it's an early game curio and fast LP is more valuable than longer LP);
Prism -> Add dreams to recipe;
Sandcastle -> Increase even more the time from 87 to 120 hours, increase LP from 7 500 to 12 500;
Of course this is my opinion, i would glad to discuss those if you want.
Why i want those:
Volva's wand -> It's an "expensive" curio and it gives low amount of LP, if you take a look into another cheaper curios( seer's bowl, seer's stone, seer's spindle, soap, etc)
rattle-tattle-tallisman -> They're almost good, they use a good amount of material but they're slighly out of "value", early game they're expensive, late game they're worthless.
Seer's tea leaves -> They would be good early game, but anyone has the material to craft team early game.
Dark Effigy -> I like it as it is, but they're quite expensive, increasing the time to refill them would be a good buff IMO.
Crabshell -> Crab wounds are impossible to heal, it's a okay curio but the price to craft them are expensive ( the wound ). Decreasing the time on them would make people grab crabs more offen and would be more rewarded for the wounds.
Nine-tails -> They would be a really nice curio on q150, but it's impossible to increase it's quality over than 60q;
Oak spire -> They're good early game, but planting oak early game is not that awesome. Increasing it's LP would be good for those who plant oak and have already a q200 tree and would be more rewarding for early game.
Primitive doll -> I guess it's a early game doll but it's too expensive, it's true that the itens used on the craft are easily able to grind ( wood, string, ashe), but when you grind enough those you will never make primitive doll again. Increase the LP for the newbies;
Cornucopia -> It's a really bad curio, but it can be just bad

;
Prism -> It's a okay curio, good on mid game ( between 60 - 100 int) . But this ammount of int is just where the player starts to get in the game, so as soon prism get useful they get useless, putting dreams on the recipe would be able to increase it's quality as the player plays, making then okay for a longer time.
Sandcastle -> For me it's just a curio for who is leaving on a vacation: long time, many slots... so just increase the reward for those are leaving.