ATSEP – Air Traffic Safety Electronics Personnel are covered. Those can be found in Annex XIII – Part – PERS of Regulation (EU) 2017/373.
However, there is a general requirement in Annex III of Regulation (EU) 2017/373:
ATM/ANS.OR.B.005 Management system
A service provider shall implement and maintain a management system that includes:
(a)(6) a process to ensure that the personnel of the service provider are trained and competent to perform their duties in a safe, efficient, continuous and sustainable manner. In this context, the service provider shall establish policies for the recruitments and training of its personnel;