Должности - проверьте плиз:)

[Song4Soul]

И.о. главного инженера - Acting Technical Manager/ Acting Chief Engineer

Зам. руководителя рабочей группы - Deputy Head of Working Group

[nancy-121]

interim chief engineer

[_Ann_]

рабочей группы - Task Group i would say

[x-z]

Interim - это И.О.

Working Group Deputy Head

[bobe]

acting; vice; interim; incumbent (Currently holding a specified office e.g.incumbent mayor);
Acting chief operating officer or interim technical manager/chief engineer; acting Senior Principal Engineer - нужен контекст, и.о. гл.инженера чего? Предприятия? Цеха? Компании?

Working Group Deputy Leader/Director

[Song4Soul]

thank you!