Commercial as in the rather broad sense of people getting paid for things on the website. If the community voice acting is going to be in the final and official release, that's commercial. If it's community supplied and everyone can download it, it's not commercial. (Regardless of the fact that it is an add-on for a commercial product, it is by itself not commercial. People can still download and listen to the sounds if they want to for whatever reason, for example.)
Now, I don't know whether you followed all kickstarter updates, but Larian promoted the weresheep pretty hard. They are true bros, and value their community a lot. I wouldn't worry about the visibility of a community sound pack add-one, may it exist. ;-)
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