Inline js doesn't see inputs in WP admin, what could be the problem?

Question

JavaScript

Hello everyone!
I ran into a problem in working with the script, or rather with WP.
I made a script that creates an input on the admin page in order to enter a number into it, and he registered the yurl in other inputs according to the template
:

JS

$('body').append('<input type="text" name="mod" id="mod" placeholder="URL" >')
  $("#mod").css("position", "absolute").css("top", 643).css("left", 281);
  $("#mod").on( "change",function () {
  $('#widget-sow-button-c52-url').val($('[name="mod"]').val());
  $('#widget-sow-button-c60-url').val($('[name="mod"]').val());
  $('#widget-sow-button-c50-url').val($('[name="mod"]').val());
  $('#widget-sow-button-c50-url').val("/wp-content/uploads/2018/02/Graphics_and_illustrations/Soc_media_WEB/gs" + $('[name="mod"]').val() + "_original.zip");
  $('#widget-sow-button-c52-url').val("/wp-content/uploads/2018/02/Graphics_and_illustrations/Soc_media_WEB/gs" + $('[name="mod"]').val() + "_eng.jpg");
  $('#widget-sow-button-c60-url').val("/wp-content/uploads/2018/02/Graphics_and_illustrations/Soc_media_WEB/gs" + $('[name="mod"]').val() + "_ua.jpg");
  $('#dcmsefi_url').val("/wp-content/uploads/2018/02/Graphics_and_illustrations/Soc_media_WEB/gs" + $('[name="mod"]').val() + "_ua.jpg");
  $('[name="post_title"]').val("gs" + $('[name="mod"]').val());
 });

He does everything BUT when I enter a number, he changes the value only in visible inputs, and he does not change those that need to be opened. (although they are on the page

f12

)
example:

spoiler

He does not fill in because he does not see them, he decided everything with a crutch:

crutch

$('body').append('<input type="button" value="Н" id="btn6" accesskey="ф" style="border-width: 0px; background: url(images/opacity.png);">')
  $("#btn6").css("position", "absolute").css("top", 300).css("left", 600).css({ color: "red" });
  $('#btn6').click(function(){
      $('#widget-sow-button-c52-url').val($('[name="mod"]').val());
  $('#widget-sow-button-c60-url').val($('[name="mod"]').val());
  $('#widget-sow-button-c50-url').val($('[name="mod"]').val());
  $('#widget-sow-button-c50-url').val("/wp-content/uploads/2018/02/Graphics_and_illustrations/Soc_media_WEB/gs" + $('[name="mod"]').val() + "_original.zip");
  $('#widget-sow-button-c52-url').val("/wp-content/uploads/2018/02/Graphics_and_illustrations/Soc_media_WEB/gs" + $('[name="mod"]').val() + "_eng.jpg");
  $('#widget-sow-button-c60-url').val("/wp-content/uploads/2018/02/Graphics_and_illustrations/Soc_media_WEB/gs" + $('[name="mod"]').val() + "_ua.jpg");
   });

Outcome:

1. I open the page
   
2. put number into input
   
3. I go through all the "languages" of the buttons, open it and press alt + f to change the value
   
4. save
   

Ideally, there should be 3 points and 2 seconds of work.
I wanted to simplify filling in the content, but anyway you need to open each button to change the url, I simplified it only at the copy-paste level, but I would like to just enter the number and save it, and not press a bunch of buttons, since there is a lot of content.
Here's what the buttons look like at the client level:

spoiler

If you need additional information, I will write, otherwise I don’t know what input parameters are needed to solve the problem.
Thank you!