Hello Nil!
First of all let me say I'm definitely not an expert, since I've never reached that level on my ED and never been hunting there sadly (I'm about to hit 279 recently). But I've been reading and watching some videos about it, and I think I can give you my point of view about this.
I would first change some of your set choices and let me explain why.
Gnome Helmet its fine if you obviously are Imbung it with Powerful Void and Powerful Epiphany, it provides good amount of physical and energy protection and adds a good amount of magic level. With both epiphany and void will make it more sustainable.
Dwarven armor its a viable option. Yes you're loosing some magic level attribute but well, after making the math, that bonus physical protection is good, and I'm assuming you don't have Soulshroud which is the best options by far. You could also try a Dream Shroud or Thundermind Raidment, but you'll lack of death defense here. If you want to go full Elemental protection and without loosing The possibility of imbuing with life leech, Elven Mail could fit.
Cobra Rod: I disagree at this point. Even though the damage of the rod its totally insignificant, Lion Rod would work much better. Has native Critic attribute, leaving the option of get Epiphany and Void on rod, making your damage higher and sustainable. The more you Hit, the more you recover.
Dwarven Legs: Not much to say here. Gnome Legs are definitely best option here but are very expensive.
Lion Spellbook: Imbued with death defense sounds good. You con go too with Umbral Master Spellbook with death protection imbue too and add some energy protection. And thought about this because Flimsy doesn't only hit hard with death, he also does with energy damage. Surely you would lose some physical protection, but if the whole point its preventing then to catch you. I would focus on elemental damage here.
Other Items protection: Bone fiddle: I also think its a must here with the Prismatic Ring. And for the necklace, I'd go with Theurgic or Prismatic one if you want to add more energy protection. Another viable option could be Koshei Amulet and Ring of lost Soul.
Now let's go where you came here to: Charms.
Bot mean and flimsy are super weak to Holy damage (Mean are 10% more weak). So I would go with Divine Wrath on Mean and maybe Cripple could go on flimsy actually. Adrenaline burst or Numb could also be good options, but its surely personal here.
Hope I helped! If I didn't, I'm so sorry. Wasn't my intention, hahaha. Have a good hunt and let us hear how it went!!