15:54 Jul 29, 2006 

Thanks to everyone for their helpful suggestions and discussion.
I think copista is the right word (vs. escriba, per DRAE) An escribano would be historically accurate for some of their roles but not in this case.
Errors in Textual Criticism(TC) tend to be viewed as unintentional until proven otherwise. There are other terms for "intentional" distortions. In this case, a "deliberate error" is a bit counter to the author's argument.
Perhaps one could argue that "garble" refers here to a consequence, rather than an action, of scribal transmission. On that basis I hesitate to render it as something intentional.