This paper focuses on delivering quantified results for the evaluation of the aggregated impact of stochastic antenna misalignment, multipath fading and hardware imperfections on the terahertz (THz) wireless fiber extenders. In this line, we present the appropriate signal model that accommodates the different technical and environmental parameters. In particular, it takes into consideration the antenna gains, the central frequency, the transmission range, the environmental conditions, i.e. temperature, humidity and pressure, the spatial jitter between the transmitter and receiver antennas, which results to antenna misalignment, the intensity of hardware imperfections, and the stochastic behavior of the wireless channel. Based on this model, we assess the joint impact of antenna misalignment and multipath fading, by providing Monte Carlo simulation results for the channels ergodic capacity.