Death Hole glitch / Grotto warping

Update: I made it so you can edit, if there is abuse then I could change it to be via email (if it happens)

A large chunk of this can be generated via running some queries on Ocarinabot's database

Does someone understand why there is a difference between returning FW from an entrance in DH mode and going to that entrance from somewhere else ? It's look like it gives you different coordinates.
For example if you go from market towards the ToT in DH mode it places you in front of boss room door in Fire Temple (as expected) but if you cast FW from market to outside ToT in normal mode and then DHWW it also places you in Fire temple but in the second room with only the first room loaded...
It seems like it's better to go through the entrance in DH mode instead of returning FW to be sure to get in bounds

Benzouz wrote

Does someone understand why there is a difference between returning FW from an entrance in DH mode and going to that entrance from somewhere else ? It's look like it gives you different coordinates.
For example if you go from market towards the ToT in DH mode it places you in front of boss room door in Fire Temple (as expected) but if you cast FW from market to outside ToT in normal mode and then DHWW it also places you in Fire temple but in the second room with only the first room loaded...
It seems like it's better to go through the entrance in DH mode instead of returning FW to be sure to get in bounds

The coordinates and map number are stored where you set FW, so it's using the coordinates and room from outside ToT, but putting you inside the fire temple scene.

Yes but what I don't understand is why doesn't it do the same when you go from the market to outside ToT in DH mode

Because in that case, it's taking you to fire temple still and it's simply taking you to the entrance that is volvagia's room->fire temple. Theres no additional room number/coordinates that you are being taken to like there is with farore's wind.