Reach the Dwarf and unlock the shop
Meeting the merchant and understanding the merchant are separate milestones. A clear passage proves your tool was strong enough; it says nothing about your museum collection.
Clear the side passage
Enter the mountain mine lobby but stay on the entrance level. Face the obstruction east of the lobby. A Steel Pickaxe or better breaks the rock; a bomb can clear it earlier. If using an explosive, place it near the blockage and move away from the blast. Walk through and talk to the Dwarf. Unreadable dialogue at this stage means you reached the correct character.
Target the missing ribbon instead of farming all four again
Check what the museum has before planning another mine trip. For Scroll II with the green ribbon, hoe tillable soil on floors 1–39 or hunt eligible enemies such as Dust Sprites. For the blue Scroll III, Blue Slimes in the icy section are a useful target. For the gold-bound Scroll IV, work tillable dirt on floors 80 and below in the descent. A hoe swung at solid stone produces nothing: bring the hoe for soil and the weapon for monster drops. Drops are random, so one empty trip does not invalidate a route.
Donate the set, then collect the reward
Gunther needs Scrolls I, II, III and IV as four different museum donations. Carrying four copies of one colour or giving the items directly to the Dwarf does not complete that display. Once the set is in the museum, collect the Dwarvish Translation Guide from Gunther’s rewards. Return to the chamber and speak to the Dwarf again. Readable dialogue and access to the merchant are the practical check that the reward applied.