You’re spot on about geometry.copy float-ifying the data via getVerticesData!
Regarding getData(), it returns the full underlying buffer, which can be shared across vertex buffers. This isn’t immediately obvious from the code doc (I’ll make sure to clarify that). A good example of when this would cause problems can be seen in this glTF with interleaved vertex data: https://playground.babylonjs.com/#88CB6A#188
On a broader note, many of our vertex data APIs were originally designed with float data in mind. It’s something I’d like to revisit. But for now, here’s a focused fix: Geometry: Preserve VB types on copy by alexchuber · Pull Request #17196 · BabylonJS/Babylon.js · GitHub. Let me know how it fares in your local project.