I think it’s a bit more complex than that:
HLR will do its reconstruction *based on the coefficients in the WB module" as that’s all it has available.
Those coefficients vary with the illuminant, in @priort 's example:
legacy : 5651 K, coeff(R) = 2.312, coeff(B)=1.545
modern: 6502 K, coeff(R) = 2.382, coeff(B)=1.389
As expected a small difference in coefficients, pushing colours towards blue when lowering the colour temperature.
But in both cases, the HLR module (in “clip …” or “reconstruct in LCh” modes) will correct to neutral gray/white relative to the coefficients in the WB module as that’s all it has to work with. And that’s exactly what we want in the “legacy” case.
It also works that way in the “modern” case, so after the WB and HLR modules we again have neutral highlights
Now we add the color calibration. That’s basically adding another WB correction (for the case that we’re dealing with here). But in most situations, that means we correct to a lower colour temperature: typical sunlight would be about 4200 K, which is a lot cooler than the camera reference of 6502 K. So all colours will be pushed towards blue, including our nice neutral corrected highlights, which will turn blue(ish).
Of course, we’re talking highlights, so filmic tends to push them back to neutral white when white reference is lowered enough. But that also tends to kill the details/texture we wanted to recover with LCh reconstruction…