In the first movie Morticia clearly states that the family credo is "Sic Gorgiamus Allos Subjectatos Nunc" yet if you look closely at the image of the stone carving of the credo it reads "Sic Gorgiamus Allos Subjectos Nunc".

Subjectos translates to Subjects while Subjectatos translates to Subjectos.

I guess Morticia just mis-spoke her own family's credo?

I understand the question is fairly moot considering the translation is fairly subjective and that because the language has no Native Speakers it is technically a dead language but in this instance we are TOLD one thing and SHOWN another. Taken from the movie the translation of the credo would read:

Thus Gorgias Allos Subjects Now

Literally translated to latin the credo should read:

Libenter epulamur iis qui nos subigerunt