I am from the US and I have not heard anyone paying taxes on the $40k as a US citizen. I can not say if this is the correct way to handle it or not. Since the money is split up between the team it is a bit complicated if you have more than one team member, but the money does get reimbursed to the head team member so if someone was responsible for paying taxes on it, it would be the head team member. All charges that you submit for reimbursement must be made from an account of a human team member on the contract or a Chilean company, and not from a US entity such as an LLC.
You can elect to draw a small salary from the grant money here in Chile (which most do) and you must register with the tax office here, but the salary is not high enough to require you to pay taxes here in Chile either.