Project.importFiles(['']) returns true, but false is expected because the given path does not exist. Running the method will briefly show the import dialog and focuses the project panel.
const app = require("premierepro");
const proj = await app.Project.getActiveProject();
const success = await proj.importFiles([""]);
console.log({ success }); // { success: true }
This matches the pattern reported for importAEComps in June: the promise resolving true looks like it means the request was handed off to the importer, not that the input was validated or that anything actually landed in the project.
Since the boolean won’t flag a bad path, doing the check yourself before the call is the practical guard — resolve each path through the UXP file-system API and skip the ones it can’t open. If you also need to know whether media really arrived, compare the project contents around the call (for example the children of getRootItem()) instead of trusting the return value.
With [‘’] specifically, the import dialog still coming up suggests the empty string is passed straight through rather than rejected up front.