I’ve already answered you in an email, but since this will be helpful to the future users, I also wanted to post it here.
Best way to redirect users on submit in SharePoint is to use fd.spSaved() event. For more events, check out our Events documentation.
The code could look like this:
result.RedirectUrl = 'http://plumsail.com';
Providing different forms for different users is currently limited as SharePoint Modern webparts do not have audiences, but there are other options that can be used.