for me it seems random

So do the NPC's have some kinda schedule when they appear ? I talked to the first guy,saw the chick and the 2 boys ,then ignored them like you said so I can get the mount first,I reached the little town beyond the broken bridge and said hey let's check if they are still there,suprise they are not.
Tried sleeping and going at different hours and no dice.

thanks for the info, i updated the guide

Some additional info:

Event: Off My Chest:
- At Tier 3 they plece 5 chests all around the place, and give no clue of their whereabouts. Entry fee is 1000 Heyrs.
- In my experience, the chests are always placed right next to some rock wall or big stone. This applies to all tiers of this event.

Event: Help with malpractice:
- Fireleaf Bellows should be used in case of any issues with breathing, like cough, no voice, etc.
- Crystal Needle should be used for mental issues.

Event: Recover Nekaroo plushie:
The reward scales up with the heroes. That means getting apex stones in the endgame stages.

Event: Save the Pilitch Breeder:
The Croctas to be killed scales up as well, and will always give a decent amount of XP.

Event: Beat the ♥♥♥♥ out of some soldiers
The soldiers' level also scales up. Beating those four always yields so much XP that is worth a half level up.