You may have been too late to stop him for murdering the first magic selling guy, since he sticks around even after you finding Sage Freke, but the other two NPC's dissapearance's are normal.
The guy in remorse that you are refering, is it the guy sitting on the stairs by the first archstone, or is it the guy who guards your excess inventory? The priest that sold miracles dissapears once you find Saint Urbain.
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CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
