I have no direct knowledge of the system Costa uses, so can't comment at all on if your information is correct or not.
Though I'm surprised to see you say the base salaries are $1049 Euros per month. On most cruise lines in the mass market, those staff are paid $50 per month, and the balance of their incomes come from the tip pool.
So.. it could be that the tip pool is already considered in the $1049 amount.
I know I've talked to the crew about this pooling system on many of my cruises, and most I've spoken with prefer it. They say with the pool system they basically know what their income is going to be from week to week and month to month, without having to worry about people "stiffing them" (which before the implemenation there was about 18% passengers not tipping).
The other thing... on some lines, even before the "auto-tipping" was put in place, and passengers tipped directly, the staff were expected to turn in their tips, and the were pooled.
From what I understand now... if passengers tip over and above the auto tip, individual staff are now allowed to keep the extra $ for themselves.