The system generates the training records (with pre-determined values) when
If you add one or more persons to group, and that this group is either directly the training group of one or more documents, or indirectly affects the training group of one or more documents (e.g. you added users into a sub group of a training group : you can have nested groups), then the system will check if the training records for these users are present, and will create the missing records if needed. Note that the process will only check the current document version (not disabled, not on approval AND available in time) to generate the employee training records.
If you update the training group of a document, then the system will check if the training records for these users belonging to the training group are present, and will create the missing records if needed.
When a document is issued (after passing the approval flow / or after submission if no approval flow configured), the system will create the training records for the given document.