Twenty is more than he expected, and a significant amount of work, but... it's also a significant amount of gold. With that, Glaffin might be able to fund something more lucrative or rent himself a workspace to try and puzzle out his vision.
"It's early in the day now, and if I get back to the caravan I can purchase the supplies I need from one of the other merchants there. Scribing that many would be about twelve hours work, so I should be able to get it done in two days for you, leaving me time to contemplate the words of Tharius and perhaps sell some of our wares from Seabreak each evening. At your leave, I can go there and come back now with the supplies for the first half of them, and once those are given to you and paid for I'll have enough to cover the second batch I can make tomorrow." He seems eager to get to work at last, but there is one last thing.
"Would you prefer the spell of slow healing, or the one that heals somewhat less but provide instant relief? Obviously those two are both strong and more stable in their effects than a simple cure spell, though the instant one only works on members of Thariusian faith, as I mentioned." It seems to him that a church would have less need of what was largely considered a combat healing spell among the dwarf clans, so he would lean towards the more powerful and slow spell of vigor if given the choice. What the customer asks for is what he will ultimately provide though.