"His boss has always barked at the staff."
Translation:Son chef a toujours aboyé sur le personnel.
No, the imparfait, while conveying an unspecified length of time, refers to the past. The passé composé serves as both the past perfective AND the perfect, and it's the perfect that is meant here. If you are unaware of the grammatical term "perfect", it refers to actions beginning in the past that continue to affect the present, which is what they mean by "has always barked" (he has barked before and continues to bark now).