The framework is so new, trying to justify your decision based on State of JS surveys over the last three years is asinine at best - svelte's own UI framework[1] is not even at 1.0 (has only recently been renamed to sveltekit).
Furthermore, there's a literal migration guide[2] to bring your app from vue 2 to 3. It's not easy. It's not painless. But being on vue 2 is equally painful. I'm also not sure what documentation or development this person is referring to because "restricted global access" is just patently false for both vue 2 and 3 - I don't even know what to cite here because it boggles my mind so thoroughly that I can't even conceive where you would come up with that "fact." Is this someone who's never opened their root app file? The place where one can pipe anything from decorators (and yes, enums???) to entire packages globally?
[1] https://kit.svelte.dev [2] https://v3-migration.vuejs.org/