Some Word APIs does not work on IE11 built in one-time purchase Word 2019

Question

I'm developing a Word add-in and trying to support IE11 built in one-time purchase Word 2019.

I noticed when I run the following code samples, they don't work but with 365 Word 2019 or one-time purchase Word 2019 with Edge, they work.

   JavaScript  
   Word.run(function (context) {  
     var FindTerm = 'some term here';  
     var searchResults = context.document.body.search(FindTerm, { matchWildcards: true });  
     context.load(searchResults, 'text, font'); // Does not work  
   });  



   JavaScript  
   Word.run(function (context) {  
     return context.sync().then(function () {  
       // Some code  
       return context.sync();  
     });  
   });  

I set the version to 1.3 in my manifest file like below.

   xml  
       <Requirements>  
           <Sets>  
               <Set Name="WordApi" MinVersion="1.3"/>  
           </Sets>  
       </Requirements>  

• context.load()
• context.sync()

Don't they work on Word 2019 with IE11 or the problem lies somewhere else?