Curvature has flipped intensities across hemispheres

Dear HippUnfold-team, I'm wondering whether there might be an issue with how we run HippUnfold or with how the curvature is calculated. We still used `v1.5.2` for this one.
When you look at the group-level curvature map that we generated,

you can see that the intensities are flipped instead of only mirrored. For comparison, gyrification and thickness maps are only mirrored:

I've loaded an individual `sub-XXX_hemi-L_space-T1w_den-0p5mm_label-hipp_curvature.shape.gii` file in `wb_view` and verified that this is not due us accidentally flipping something when calculating the group-level maps. I am wondering whether this is an issue because in DeKraker et al. (2022) the curvature maps looks mirrored not flipped like the rest of the maps:

Source: https://pmc.ncbi.nlm.nih.gov/articles/PMC9831605/

Start by reproducing the group-level curvature map from the individual sub-XXX_hemi-L_space-T1w_den-0p5mm_label-hipp_curvature.shape.gii file using HippUnfold v1.5.2, and inspect the result in wb_view. Compare curvature with the gyrification and thickness maps to identify where intensities become flipped; done means determining whether the issue is in HippUnfold or the curvature calculation and documenting the corrected behavior.

Written by the indexing model from the issue text.