1. Ensure that the language change is successfully being saved in the user's profile. You can check this by verifying the lang field in the res.users model for the user.

2. Add a custom function to handle the language change and force Odoo to reload the session using JavaScript.

Here's a modified version of your JavaScript code that includes a function to reload the session after changing the language:

/** @odoo-module **/

import { Dropdown } from '@web/core/dropdown/dropdown';

import { DropdownItem } from '@web/core/dropdown/dropdown_item';

import { useService } from '@web/core/utils/hooks';

import { registry } from '@web/core/registry';

import { Component, onWillStart } from '@odoo/owl';

import { session } from '@web/session';

import { browser } from '@web/core/browser/browser';

export class SwitchLanguageMenu extends Component {

setup() {

this.langService = useService('lang');

this.ormService = useService('orm');

this.userLangCode = session.bundle_params.lang;

onWillStart(async () => {

this.langs = await this.langService.getLangs();

this.lang = this.langs.find((l) => l.code === this.userLangCode);

});

}

async switch(lang) {

if (this.lang === lang) {

return;

}

await this.ormService.write('res.users', [session.uid], {

lang: lang.code,

});

// Clear the language cache to force Odoo to apply the language change

session.lang = lang.code;

session.user_context.lang = lang.code;

browser.session.session_reload();

// Use the following if you want to refresh the whole page instead of just the session

// window.location.reload();

}

}

SwitchLanguageMenu.template