Finish up a multi-step Django form

I have a website which helps youth sports leagues manage their registration, team assignment, communication, and scheduling for their players and teams. I have a 6-step Django registration. It enables parents to register multiple children for sports and activities. The first step displays the activities from the selected organization that are open for registration and for which each child is eligible (based on age, grade, and/or gender). There is also a setting for each activity that collects uniform sizes and uniform payments if the organization has configured them. The second step is just a straightforward address form. The third step collects volunteer information from the parent for each child/activity pair selected, so it must use the selections from step 1 to create the volunteer information. The fourth step is a series of custom waivers that must be acknowledged - some are required based on the settings of the waiver from the organization. Again, these use the child/activity pairs from step 1. The 5th step is a summary of all of the prior 4 steps of information. The last step is to process either an offline or online payment and store the information from the forms. The previous developer coded all of the validation and data processing on the client side in JavaScript, treating the form as one big form rather than 6 individual forms. He then submitted all of the information at once via JavaScript for processing. The website, including the registration form, has been redesigned (Bootstrap 4), which has invalidated all of the previous JavaScript. The JavaScript was not documented. Being a JavaScript novice, I'm having difficulty understanding what the scripts are doing so I can't amend them for the new design. I'm not averse to the approach he used, but if done that way I need the scripts to be well-documented (and preferably in a separate file). It would likely be easier to do it that way and conform to the already defined views. I'm also not averse to redesigning the process to use django-formtools and a multi-step approach which includes server-side validation after each step and session variables to make navigating between steps possible. In many respects that might be the preferable approach; I'm open to advice/opinion on this. I have a functional staging environment already configured with all of the code and all of the Django apps (including django-formtools).