υπηρεσιακός προπονητής
μεταβατικός προπονητής → caretaker manager, caretaker coach, interim manager
In association footballing terms, a caretaker manager is somebody who takes temporary charge of the management of a football club, usually when the regular manager is dismissed, or leaves for a different club. However, a caretaker may also be appointed if the regular manager is suspended, ill or unable to attend to their usual duties. Caretaker managers are normally appointed at short notice from within the club, usually the assistant manager, a senior coach, or an experienced player.
The term "caretaker coach" is used in Australian rules football, and in other sports, the term "interim manager" is more commonly used.
https://en.wikipedia.org/wiki/Caretaker_manager