You should not use the same name in a dialog (I assume that is what you mean).  As Ravi points out - you would have conflicts. Best practice for working with dialogs and Granite can be found here - Building Experience Manager Components using Granite/Coral Resource Types

I will ask the presenter to look here.

Did you watch our Ask the AEM Community webinar on this subject? Scott's Digital Community: [Webinar |October] AtACE Session: Creating a site structure to support your global business

Are you seeing any messages in the log file. I have never attempted to change password via CURL.

see if this helps - How to refresh a page when a component is modified

On Author - when you drop a component and enter values into the dialog and click the done button in the dialog - the page refreshes and you see the component rendering the values you entered into the component. Is that your experience?

Example here - Adobe Experience Manager Help | Creating Java Swing applications that posts files to AEM ClientLibs folders

Also - just so you know - the article that you referenced was for AEM Form that you create by using AEM Foundation components. If the form core component does not meet your needs - look at using the foundation form components.

Is it not submitting to post.POST.jsp?

You should look at hooking into Analytics - see this to learn how to work with AEM and other services -- Adobe Summit 2019 | L725 - Building a Web Experience Foundation with AEM, Target, and Analytics