To Tim, Reply #1...
Right, but it almost seems to you're suggesting that misalignment betwen the leadout guides and the bellcrank arms, might affect the model's yaw angle. Claus Maikis published a nice article about this in (I think) the 1970's, in an Aeromodeller issue. Several photos of a cardboard cutout of the top view of a model with the bellcrank pivot, CG and leadout 'cables' marked with pins. The thread ran from the leadouts to the bellcrank pivot. The cutout was ballasted so the CG was at the positions of its pin, when that was changed. This rig was hung vertically...
Result: wherever the CG was located, the "leadouts" aimed at the CG as they passed through the "leadout guides." Moving the "guides" for a particular CG position yawed the "model" accordingly. Moving the CG for a given leadout "guide" position did the same thing.
Moving the bellcrank pivot did nothing. Any push fore or aft occurs inside the model structure, not outside, where it could affect yaw trim.
As several mentioned, a bellcrank pivot badly located makes leadouts bend through the guides, INSIDE the wing, which can produce friction, possible wear, and perhaps even stiffer control 'feel.'
BTW, testing how free the controls feel, without the load of in-flight pull, could be misleading.
Very good point about crosswind yaw effects - it's a good thing we fly analog, not digital. We correct for the difference by reflex, if it is stronger than usual, or instinctively without noticing it, in less severe crosswinds...