I've killed more than 20 of those and still haven't got the title.
EDIT: ok, we have to kill only the Quick ones, not the regulars.
There is only 15 spots for them on the map.

You need to kill this "Quick" type.
https://imgur.com/b5QcKNI

我有尋找到了正確找到敏銳草刺蝟與敏銳犰狳的方法
教學文章:https://forum.gamer.com.tw/C.php?bsn=19017&snA=63591&tnum=3&subbsn=14
教學影片：https://www.youtube.com/watch?v=K1AiEtuISnA
觸發方法片段：https://youtu.be/K1AiEtuISnA?si=xcuqaOUXZIipwV6I&t=38

大家必須要尋找到他們的影子！
敏銳犰狳位置：https://bdocodex.com/th/npc/20727/
敏銳草刺蝟位置：https://bdocodex.com/th/npc/20726/
Stonebeak Shore那邊的位置被標註的很奇怪，敏銳犰狳的位置非常分散！敏銳草刺蝟的位置是正常的！

From Taiwan server