Agree with all these potential issues, which is why there has to be a properly considered process that looks at all eventualities, led by people who are expert in those topics. So for example biological statisticians that can model population growth depending on conditions, habitat, food, intervention etc, so that we have better visibility in advance of likely scenarios.
There must also be an exit process in case things don't go as planned and a strategy to maintain populations within the modelled range that limits negative impacts to the acceptable level determined at the start (there will be some - we have to be realistic about all consequences and have agreed ways to address them).
One option, for example, is to only release sterilised animals so that they can't breed and then you have an ability to see what a distinct population does with no danger of it growing out of control. This is an option we're looking at on the African side for reintroduction of lion into a closed system as we are concerned about the potential negative impact on other predators (especially cheetah and wild dog, who will be targeted by lion as competitors).. but I digress.
However we all also have to recognise that this is far more complex than our gut feelings and that the positive or negative impact on us or the aspects we individually value most are not the sole drivers of any eventual decision.