Localize custom form in wordpress / wpml

What I am trying to achive?

I have a feedback form which is handled by a java servlet. This servlet expects a parameter locale for the currently selected language (see code below at xxx somehow put the current language there xxx). We want to migrate our current system to Wordpress / wpml. We will probably need to adjust our servlet.

The example use case should go like this:

1. open feedback form
2. enter name/email/text
3. submit

The code of the feedback form is as follows (and is embedded in the DIVI page as module code):

div class=form-contact
    form id=feedback action=/feedback method=POST name=feedback
    div class=row
        div class=col-md-6
            div class=row control-group
                div class=form-group col-xs-12 controls
                    label for=nameName:/label 
                    input id=name class=form-control name=authorName type=text /
                /div
            /div
        /div
        div class=col-md-6
            div class=row control-group
                div class=form-group col-xs-12 controls
                    label for=emailEmail*:/label 
          input id=email class=form-control name=email required= type=email /
                /div
            /div
        /div
    /div

    div class=row control-group
        div class=form-group col-xs-12 controls
            label id=comment for=commentYour comment:/label
            textarea class=form-control cols=60 name=comment required= rows=10/textarea 
        /div
    /div

    div class=required ( * fields are required)
  /div
  input name=locale type=hidden value=xxx somehow put the current language there xxx /
  div id=success
  /div
  div class=row
    div class=form-group col-xs-12
      button class=btn btn-theme-bg btn-lg type=submit value=SendSend/button
    /div
  /div
    /form
/div

Expected Result: The response page should display in the correct language

What are we currently using?

• Wordpress 5.8
• DIVI 4.9.4
• WPML 4.4.10

What did we already investigate

• https://barebones.dev/articles/wpmls-icl_language_code-constant-always-returns-the-default-language-within-ajax-functions/

• https://wpml.org/documentation/support/wpml-coding-api/

I have no idea how to get the currently selected language of Wordpress into the form parameter. I have the impression that I am asking a ridiculous question. Perhaps the way I want to resolve this issue is completely wrong.

A possible approach Perhaps I need to write in functions.php the value of ICL_LANGUAGE_CODE to a javascript object and use this in my custom form code on my Wordpress page? But this seems by far too complicated?