From the looks of it, you know more about electricity than me. But, I was thinking ...
1. The voltage drop problem is the reason for the multiple taps on the transformer.
2. By using the 14v tap, I would use fewer amps than at 12v, therefore producing less heat and leading to less socket corrosion.
3. Low voltage (12v) lighting is, by definition, high amp (~25 amp) lighting, everthing else held constant (300w). Since many pools use low voltage lighting, I do not think my problem is not correctable by some fine tuning of my power source.

When using the 12v tap on my transformer, and compensating for voltage drop, I suspect that my load was 30 or more amps. By moving to the 14v tap, compensating for voltage drop, my load should be ~25 amps, or ~20% less. That should positively impact my suspected heat problem.

Rather than waiting another year, I was hoping that this would be an identified problem on this forum - someone choosing the wrong tap on the transformer leading to frequent bulb socket corrosion.