"Rating" is not the same as Percent. I recently read a post by Nephele on that subject. Can't find the link, but he said that it should require a great deal of 'Rating' to max out one's Percent.
And a +18 without any descriptor is even more vague.
Yes, it's confusing and hopefully they will make stat descriptions clearer in the future.
No I get that part. The formula could be a small or large exchange. My observation is that +2 & +18 are both yielding exactly 1% gain.
The character sheet displaying the 2nd decimal wouldn't require rounding that severe. Was there separate devs working brewing and cooking with their own formula? Is one an old recipe vs. a new recipe after formulas got adjusted? Is it just a typo that needs correcting? /shrug