Swift Package storyboard localization

Question

I'm trying to create a Swift Package with a localized Storyboard inside (following the Apple docs). Let's say my package manifest is:

// swift-tools-version: 5.6
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "MyPackage",
    defaultLocalization: "en",
    products: [
        .library(
            name: "MyPackage",
            targets: ["MyPackage"]),
    ],
    targets: [
        .target(
            name: "MyPackage",
            dependencies: [])
    ]
)

I want my package to contain a localized Storyboard, so I created a structure like this:

where main.strings in en.lproj is:

"T63-i3-Tqi.text" = "Hello World";

and main.strings in it.lproj is:

"T63-i3-Tqi.text" = "Ciao a tutti!";

Then I link this package to an app and I set the app localization to both english and italian. Unfortunately, though, when I change the app language nothing changes. I mean, the app always takes the english localization of the Storyboard. Can you help me? Thanks.