So, you are saying to use the citric acid type of recipe where you add it directly to the milk?
I typed too fast. My real point was that with mozz and goat milk, especially high calcium, large-micelle milk like Nubian, it takes time and acidity to break down the calcium bonds and hydrate them so mozz can stretch. To do this, you can rennet at a lower pH, say 6.4, and drain at a lower pH, like 6.0-6.1, and wait for it to stretch, or pre-acidify while the milk is still liquid. The key is the acid + time.
If you do the direct acidified, after it sets up, let it sit for 20-30 mins so that it has a lot of moisture retention. It will set quickly, in 3-4 mins. The set time and cut size of curds determines moisture retention. And for goat milk, for citric direct acidifed, target pH is 5.7. If using acetic, target 5.6.