Fix Custom Wordpress Functionality

My client has a Woo-commerce site and he had requested to import 4000 users through a csv file with some custom fields. After importing all the users with the custom fields he wanted to achieve two things: 1) Insert one of these fields in the user's page (my account page) when they log in 2) With every new order, this custom field should be displayed with the notification email ([login to view URL] file) I had managed to insert a custom php code and achieve this, however for some weird reason after a year the custom field with the email notification stopped working (potentially due to a Wordpress update). The custom field in the "My Account" page is still working. This should be a really quick fix for someone that works with PHP. Only problem is that since I don't have the time to work on this there are still a lot of updates for the website that will most probably break the site if I perform them so the fix should be tested in an environment with the current version of Wordpress and plugins.