I have provided an example where "HelloWorld" and "Hello World" behaves differently when using .layout. Without spaces, it is able to be laid out. With spaces it crashes. This is using the Gugi font from Google.
Font here: https://fonts.google.com/specimen/Gugi
A minimal reproducible example may be found here: https://codesandbox.io/p/devbox/pfjgyf. NOTE: you may need to fork this, I was having troubles getting FontKit to be picked up in the import.