I see a bunch of issues with those pictures. First off your rudder pull pull cables are slack. This means that around center stick you have zero rudder/tailwheel control. This is going to setup a time delay of when you actually get some result from Stick movement. Part of why you have that situation is that it appears in the picture your rudder horn pivot point is well in front of your hinge line. If this is the case you may have loosened the cables at center to keep them from being puller overly tight due to the offset between the hinge line and the horn pivots. Ideally on a pull pull setup the clevis hole in the control horn would line up with the hinge line. Then the servo arm and control horns would be the same width but not absolutely nessesary. This would really help in keeping the cables tight throughout the entire movement.

The next item is probably more of an issue. You can't run a hard single linkage on a tailwheel like you have. The tailwheel strut will flex and that in return will create a directional input. If you look at your picture, the wheel looks straight. When the airplane is at rest with some weight on the tailwheel the strut will flex up and introduce a right input. Holding up elevator with airflow over the tail ( taxi and take off ) and you will be applying more downforce which will input even more right input. My suggestions going forward is to sort out your pull pull cables or move your rudder servo to the tail as your CG is currently very conservatively forward. Then fabricate a tiller arm shaped like a T and install as per the drawing. Those alone will go a long ways to solve your issue. For a complete fix, moving the wheel axles back some either with a new gear or by installing a wedge between the gear and fuselage and my throttle linkage fix. IMO 1:1 servo/throttle ratio is still far from ideal.