The rules given in the books, whether in the Narrator's Guide or the Creatures supplement, are a mess. But, as far as I can tell, creatures created with the rules from the Narrator's Guide look ridiculously feeble, and require tens of thousands of XP to become equivalent to the creatures depicted in the eponymous supplement in terms of stats.
I've looked online, including on Beyond the Final Frontier, but I couldn't find anything about the creatures: no errata or even someone doing an homebrew system.
Did I miss something in the original rules or in Creatures?
This question is not about the card game but the RPG that Decipher created after they got the license.