SketchUp struggles to map textures onto lofts. To fix this, after generating your CurviLoft 18 surface:
As of this writing, the developers are hinting at CurviLoft 19, which is rumored to include AI-based edge prediction and cloud-based curve sharing. However, CurviLoft 18 remains the gold standard for stability, and it is unlikely to be deprecated anytime soon given the massive user base in the architectural rendering community. curviloft 18
Like a custom sweep.