I truly sympathise with you as I've had similiar problems in the past. What would be best is if you could find a local farmer who does his own slaughtering - they do exist. A farmer who just has the abattoir do it all, will have no control over anything and the abattoir people will be too limited to be able to change their inflexible routine(and won't care about the customer).
I'm surprised that US farmers wouldn't know what suet is - even UK farmers who haven't a clue about what adrenals are, do know what suet is. The trouble is that most farmers tend to slaughter their cattle too soon (2-3 years after birth), partly due to stupid government regulations and their desire to make a profit, and grassfed cattle need more time to build up enough fat. You could substitute the suet with ox-/beef-tongue which is very high in fat(50-60%?) though not as high as suet. As regards tallow, that is rendered(ie cooked) suet so is not ideal, but if there are no other sources ....
Raw butter is better than other kinds of raw dairy, in that short-term effects are much less common. But people do frequently report minor to major symptoms from it, in the long-term.
Check out
www.eatwild.com and search the site under "New York" to find some farms listed for that region.
In short, I definitely don't recommend zero-carb for anyone who doesn't have a cast-iron guarantee from one or more farms as regards regular delivery of high-quality grassfed meat with enough quality fats. So, I would suggest going back to zero-carb only when you're in a position to order from Slanker's or NorthStar Bison(US wellness seems to hvae acquired a bad reputation from other US RPDers, so I don't recommend it).