Since I'm a noob, maybe it's me who didn't understand about how things work.I'm using 16.0.0 myself, because the latest update (16.0.2) doesn't appear to do anything except remove some event quests and promotional content (https://www.monsterhunter.com/rise-sunbreak/update/en-us/ver16_00_02.html).
On 16.0.0, the PAK file name is015
. So 16.0.2 might be 016 or 017 (since there's a 16.0.1 in-between).
I'm surprised that renaming it as 099 works for someone; it didn't work for me. From what I understand, the game reads PAK files sequentially from 001 and stops once there aren't any more. So for example if the latest official PAK is 014 and the mod is named 099, I don't think it will be loaded. But perhaps I'm mistaken.
If 16.0.0 is easier to try modding, then I should update to that version.
Thank for your great tutorial! Sorry if I made any inconveniences. Have a nice day!