Improve a simple php script (json-generator)

I have assembled a basic version of the generator/editor for questionnaires .json 
it needs to finish the option to add the following questionnaires, 
make the layout a bit more compact and welcoming, 
insert a function to prevent accidental closure of the window in the browser,
and complete the save function
 
https://gaz-21.de/autoreg/jsoneditor/index.php

in ZIP = code + sample json file 

Requirements:

1. Upload JSON file

   • upon the first loading of the site, there is one empty form for the questionnaire 
   • it is necessary to keep the option to upload a JSON file from the computer (for editing an existing file)

2. Display list of items

   • After uploading the file, display a list of all questionnaires from the file in a user-friendly editing interface.
   • When uploading, convert Unicode to regular letters/smiles
   • the image should be uploaded next to each questionnaire (200x200px)
   • when filling in the field for the image URL, it should load immediately (AJAX)
   • add a button (+) at the bottom to allow adding additional questionnaires 

3. Editing each item
   For each item, the following editing fields should be provided:

   • Photo: Text field for entering the image URL (photo).
   • Badge: 4 radio buttons (3 with pre-filled content (vip, hot, milf) + 1 with a text field) for entering the badge value (badge).
   • Title (title):
     • 3x Text field for the name (non-mandatory).
     • Separate text field for age (non-mandatory).
     • these data are not mandatory, if they are empty -> then save the parameters without content
   • Description (description):
     • Three text fields for editing the description in each language (en, de, dk)
   • Looking for (looking):
     • 3 radio buttons for selecting a fixed option.
       • Option 1: "She is looking for him" / "Sie sucht Ihn" / "Hun søger ham"
       • Option 2: "looking2en" / "looking2de" / "looking2dk".
       • Option 3: "looking3en" / "looking3de" / "looking3dk".
   • Location (location):
     • it is always fixed - just ignore it when uploading, and when saving, add it to the skeleton 
   • Category (category):
     • 5 radio buttons for selecting a category "category1" / "category2" / "category3" / "category4" / "category5"

4. Generate JSON

   • At the bottom of the page, a button "generate .json"
   • letters/smiles are saved in Unicode
   • After clicking the button, generate a JSON file with updated data.
   • Provide the option to save this file to the user's computer.

Technical requirements:

• Support for modern browsers (Google Chrome, Firefox, Safari).
• Minimalist and user-friendly interface (tidy up the layout a bit (tables)
  can add some colors