It’s clear that non-idiomatic language (hopefully not with structural errors) has an effect on the mental representation of a student. It would be silly to deny that. Although Bill VanPatten advocates for teachers to have high proficiency levels in this week’s Tea with BVP, he also mentions that we don’t know for certain what the negative impact of exposure to low-quality input is over different periods of time (e.g. K-12 Spanish vs. 4 years of Latin). Regardless, I think we should be asking this:
Does the negative impact of using non-idiomatic Latin outweigh the benefits of an improved experience and inclusion of ALL students in the Latin classroom?
If the answer is “yes” in a catastrophic way, an extreme suggestion would be that all Latin teachers below X proficiency level should immediately resign, or at least refrain from creating and/or publishing materials for students. These teachers should attend the available immersion events (e.g. conventicula, rusticātiō, Living Latin in NYC, etc.), listen to Nuntiī Latīnī and Quōmodō Dīcitur, read as much Latin that they understand as possible, and then get back on the horse when they’re up to speed. A less-extreme suggestion would be that they should simply not teach Latin communicatively.
If the answer is “no,” or “yes” in a non-catastrophic way, then the teacher should still definitely seek out those same ways to improve proficiency, but perhaps with less urgency. They should certainly keep teaching, and we could certainly use the published materials.
Personally, I feel that ANY mental representation of language is more beneficial than what has been going on with Grammar-Translation, and my hunch is that the negative impact is nowhere near catastrophic. Thus, it’s only a matter of time until the teacher’s proficiency improves to a high level, which means that each year students will be exposed to richer and richer input.
Note how the most effective solutions to improving proficiency become an issue of access—the immersion events aren’t cheap, and not everyone has a local Latin conversation group with highly proficient speakers. Teachers with more money and time have greater access to understandable Latin. Note, also, how the issue of access brings us right back to the classroom. A CI classroom is about extending access to Latin to all students—students typically left out in the grammar game. Realize, too, that most Latin teachers, themselves, have been denied access to communicative proficiency, and are doing what they can to improve it.