Middlewares can help you hook into some of the html-skechapp's internals.

Text overrides in existing symbols will be lost when updating an existing library since Sketch references the randomly generated object ID. A custom text ID can be set by adding a unique identifier to the text wrapper and using that in an onTextGenerate callback, as shown below, or using the text as a unique identifier – in the form <Button>buttons/default</Button> with using node.nodeValue in the onTextGenerate callback:

<Button data-sketch-id="buttons/default">
  Default Button
</Button>

const layers = nodeToSketchLayers(node, {
  onTextGenerate: ({ layer, node }) => {
    const parentNode = node.parentNode;
    if (parentNode && parentNode.dataset) {
      const { sketchId } = parentNode.dataset;
      if (sketchId) {
        layer.setObjectID(`text:${sketchId}`);
      }
    }
  }
});