Com esta Unai?
Your English is far better than my Spanish.
It is not possible to give you an accurate answer without having more information about the size of the products you are cooking. However, i think you are cooking your meal backwards.
The Entrecote cooked at 55ᴼC will be Medium-Rare, the way most people best enjoy it. The length of cooking time will depend on the steak's, or roast's, thickness starting with the time your water bath attains the 55ᴼC setting. Steaks 25mm thick require 75 minutes, and if 35mm thick require 2 hours.
For the Red Tuna your temperature choice is exactly my choice too. However, unless the jars are very small, less than 125ml, 30 minutes may be a little too short for complete heat difusion. Consider that you are cooking the oil as well as the tuna in calculating your cooking time. The heat has to penetrate the glass and oil, and then to the centre of the tuna.
When cooking several different items continuously i always begin with the menu item that requires the longest cooking time. If all are about equal, then i start with the item requiring highest temperature. In your meal, that is the Entrecote.
When the Entrecote's cooking time is complete, reset the Anova's temperature and the water to 43ᴼC by adding cold water or ice. Then add the room temperature, not cold, jars of Tuna. (Cold glass may break from thermal shock of the hot water.) The steaks will not cook any more at that temperature and will stay warm as the tuna cooks.
You can also hold the steaks in the warm water while enjoying the Tuna. Then sear and serve, - and enjoy.