How to Find Roderika and Complete Her Quest

First Meeting - Stormhill Shack: Head north from the Gatefront Ruins, following the road until you reach the Stormhill Shack Site of Grace. You'll find Roderika sitting on the floor here. Chat with her a few times. She'll give you the Sitting Sideways Gesture and the Spirit Jellyfish Ashes. She'll also mention something about her group and a spider, which is a hint for the next step.

Finding the Chrysalids' Memento: Now, you need to make your way into Stormveil Castle. Push through the castle until you find a room just off to the side of the Grafted Scion boss arena. Inside this room, you'll see a pile of corpses. Loot the Chrysalids' Memento from the top of this pile.

Return to Roderika: Take the Chrysalids' Memento back to Roderika at Stormhill Shack. After you give it to her, she'll mention moving to a new location.

Second Meeting - Roundtable Hold: Once you've given her the Memento, she'll relocate to Roundtable Hold, usually found near the main hearth. Speak with her there, and she'll give you a Golden Seed as thanks.

Getting Her to Offer Services: This is where you need to be a bit patient. Talk to Roderika for a bit, then go find Smithing Master Hewg (he's also in Roundtable Hold). Speak to him and ask about Roderika. You might need to leave Roundtable Hold and come back for this dialogue option to appear. Keep going back and forth between Hewg and Roderika, asking them about each other. Eventually, Roderika will agree to learn from Hewg. The next time you return to Roundtable Hold, you'll find her set up shop right next to Hewg, offering her services to upgrade your Spirit Ashes.