In game I have the wrong time zone
Not an expert on minecraft. But it seems that multicraft uses php and you can adjust php.ini to have the correct timezone setting i.e edit /app/data/php.ini and set the data.timezone to one of the values in https://www.php.net/manual/en/timezones.php.
If the issue here is bedrock app, it seems we can pass timezone like this https://confluence.atlassian.com/jirakb/set-the-timezone-for-the-java-environment-323392719.html . We can adjust the bedrock app to have the timezone customizable. Is this what you are looking for?