First off if anyone hears that its made from free models he will dislike the game so dont make your game from free models also there are some bugs like if you shoot repeatedly the gun will go through the players body and if you want to make a game try as much as possible to avoid using free models
free models are just unreliable in most cases. Because they are usually unoptimized for most games (no collection service use), and are hard to edit. I wouldnt say there will be much risk in using free models because you can see how many scripts are in a free model and look through yourself. You are better of scripting and reusing models, or repurposing and editing scripts so they are more optimized for many uses (using handler scripts, collection service, etc)