This isn’t a normal global white-balance issue. If different parts of the image shift in different directions, the photo was likely lit by different-colored light, so one WB setting won’t neutralize everything at once.

The practical fix is local color correction:

• Select or mask the affected areas separately.
• Soften the selection edges with feathering for smooth transitions.
• Adjust hue/saturation or color balance only within those regions.

In GIMP, one suggested approach is:

1. Fuzzy-select the bluish roof area.
2. Shift-click to add other similar areas if needed.
3. Use Select > Feather.
4. Open Colors > Hue-Saturation.
5. Target the blue/indigo range and reduce saturation or shift it toward neutral.

You can do the same kind of region-restricted correction in darktable using masks. In short: don’t look for a special WB mode for this; use local adjustments to equalize the differently lit parts of the train.