It may not create drivability problems, such as jerkiness, that seem to be transmission related. Driving with such problems for a long time may cause damage to other components of the drivetrain.
In earlier vehicles, gearbox shifting quality and timing are determined by engine load, generally performed via engine vacuum. When the engine misfires, for example, due to a faulty ignition coil, the manifold vacuum is decreased, giving the transmission vacuum modulator incorrect load information, causing late and hard shifting. This is the degree to which it will affect transmission. If the issue is not fixed, damage to the engine is more likely than damage to the transmission.