This article addresses the event-triggered consensus tracking control problem for complex heterogeneous multiagent systems with multiple unknown. The systems under consideration involve fully unknown time-varying control directions (CDs), unknown time-varying input delays (UTVDs) and functions, making the problem particularly challenging. To reduce the effects of UTVDs, an auxiliary system is constructed to produce a compensation signal. Building upon this, a novel adaptive proportional-integral (PI) control approach is developed through the backstepping method and a series of Nussbaum functions. It is demonstrated that the tracking error can meet predefined transient and steady-state performance criteria, ensuring asymptotic tracking and global boundedness of all signals in the closed-loop system. The key advantage of this solution lies in its simplicity of controller design and improved control performance, without requiring prior information about the unknown functions. Finally, a simulation example validates the validity of the proposed approach.