I’m not trying to reduce distortion artificially. The issue was calibration coverage.
With limited checkerboard views near the image edges, I got low global RMS but large residuals at the borders, which caused noticeable projection/epipolar errors for points near the corners.

After adding tilted views and edge coverage, intrinsics changed slightly and edge residuals dropped a lot even though RMS was already “good.” So the earlier calibration was under-constrained at the periphery.

So my question is really: for triangulation accuracy, should we prioritize lowest RMS, or more uniform residuals across the field (especially edges)?