i would imagine secret rares are still the harder of the two to pull. in a full booster box, i’d think you’d only pull 1 secret rare and maybe 2-3 amazings. you can get about 1-2 amazing rares in each of the japanese boxes, and japanese booster boxes have fewer packs too.
In Japanese Legendary Heartbeat/Pulse. I am guessing the Hyper rares and gold cards to be hardest to pull.
Each booster box usually just has one amazing rare and only one SR, HR or UR Gold Card.
I don’t know if true or not but I heard of some of boxes on release having one Amazing Rare and two secret rares.
I have only opened three booster boxes, one with my daughter and have pulled two SR full arts Zarude full art & Coalossal full art, 3 different amazing rares Jirachi, Zacian & Rayquaza (luckily no doubles) and one UR toughness cloak Gold card.