When do helltide chests do appear on the minimap?
It seems to appear after a while on the map (for the first time) and if you go close to their location… and stay on map after that… but sometimes, when first time on a given map iit seems to have no chest until you stay long enough…
somewhat confused, anyone has clarifications?
Helltide chests seem to appear when you go to that section of the helltide as they are broken into sections usually by some easy to detect map feature. I agree with you though. They should just be there all the time.
looks like they didnt want to take the helltides website’s business 
still very much need it.
The chests appear once you are far enough out of town and within whichever “half” of the helltide zone (or third, for the Kejhistan HTs). It isn’t a matter of time from leaving town, but a matter of getting far enough into the respective part of the helltide zone that contains the chest. The one area where this can get somewhat annoying is around Weijhani, as that town’s border is somewhat of an outlier amongst towns. Around Kyovashad and Ked Bardu you need to get a bit further out than normal due to some lingering areas of the ouskirts outside of town that still count as being inside the town (for Ked Bardu you can easily see this by when you’re clearly outside of town along the edge in the combat field but your horse suddenly shifts all the way down to first gear instantly out of the blue).