Before a Cohen begings to dochen there is a nusach of yehi ratzon that is said. May the Cohen be mafsik in the middle of this in order to answer “Baruch hu U’Baruch Shmo”.
Answer:
There is no prohibition to make a hefsek in the middle of the nusach, because it is a personal request (bakasha) and not a formal prayer. On the other hand, there is no obligation to answer “Baruch Hu u-varuch Shemo,” though it is a good thing to do, and mentioned a number of times by poskim (such as by the Mishnah Berurah; see 122:4).
Therefore, he can choose between the options, and do whatever he’s comfortable with.
