Just suggestion:
For more politically correct, I'd just say 怪物 or 未知生物.
From your definition of cryptid, I don't find the concept equivalent to 妖怪.
Btw, 妖怪 Yōkai has a detailed wiki page you may find it fascinating:
[en.wikipedia.org]
Anyway, 怪物 is just a broad term. For truthful equivalent and to integrate the noun in Chinese, I suggest using words of similar pronunciation like toast 多士 to represent cryptid. So, maybe I'm just out of idea but I don't think there's a Chinese equivalent for cryptid.
For more politically correct, I'd just say 怪物 or 未知生物.
From your definition of cryptid, I don't find the concept equivalent to 妖怪.
Btw, 妖怪 Yōkai has a detailed wiki page you may find it fascinating:
[en.wikipedia.org]
Anyway, 怪物 is just a broad term. For truthful equivalent and to integrate the noun in Chinese, I suggest using words of similar pronunciation like toast 多士 to represent cryptid. So, maybe I'm just out of idea but I don't think there's a Chinese equivalent for cryptid.