WordPress Multisite (PenNews Theme) & Plugins Update, PHP 8.3+ Upgrade, and Weather API Fix

Hello,
I am looking for an experienced and reliable WordPress & cPanel developer to perform a maintenance and upgrade task on my existing WordPress Multisite installation (istra-sport.hr), which runs on the PenNews theme by PenciDesign.

Scope of Work & Requirements:

1. Full Backup & Safety Responsibility: Before making any changes, you must create a complete backup of the entire WordPress Multisite installation (all files and the database). Ensuring data integrity, visual layout, and full site functionality is top priority. The selected freelancer takes full responsibility for maintaining the site's current appearance and functionality throughout and after the process.

2. WordPress Core, Theme & Plugins Update (Network Level):
o Update WordPress core (to 7.1.4) via Network Admin.
o Update the active PenNews theme (currently on v6.7.4) to the latest version.
(Note: The theme license is active and the Envato Market OAuth Personal Token is already verified in Network Admin, so the theme update is ready directly inside the dashboard.)
o Update all bundled theme plugins (e.g., Penci Framework, WPBakery Page Builder, etc.) and all other installed plugins to their latest versions.

3. Preserve Custom CSS: The current WordPress theme contains important Custom CSS settings responsible for the site's design. You must safely back up this Custom CSS prior to updating and ensure it is properly restored/retained afterward so the layout remains completely intact.

4. PHP Version Upgrade (cPanel): Access cPanel and upgrade the PHP version to the latest stable version supported by the updated theme and plugins (ideally PHP 8.3 or PHP 8.4). The final PHP version must be at least PHP 8.3 or higher. I think the theme supports 8.3, though...check it out.

5. Weather Widget API Fix: The footer currently displays the message:
"Weather widget You need to fill API key to Customize > General Options > Weather API Key to get this widget work." The previous API key stopped working (likely due to OpenWeatherMap API changes/deprecation). You need to generate/configure a new working free OpenWeatherMap API key (or troubleshoot why the existing one is rejected) under Customize > General Options > Weather API Key and verify that the widget displays weather data for Pula properly.

6. Post-Upgrade Testing: Thoroughly test the entire website (desktop and mobile, all pages, menus, sub-sites if any, and widgets) after the updates to confirm there are no PHP errors, broken layouts, or compatibility issues.

**Deadline**
This project is time-sensitive. All work must be completed, tested, and verified by this Sunday, November 15, at 8:00 PM (20:00) CET (UTC+1).

To Apply:
Please briefly confirm your experience with WordPress Multisite updates, PenNews/WPBakery themes, cPanel PHP configurations, and OpenWeatherMap API setup, and confirm that you can meet the Sunday deadline**.