Fira Code/Operator Atom Less Settings

styles.less

atom-text-editor.editor {
  font-family: "OperatorMono-Medium";
  text-rendering: optimizeLegibility;
  font-size: 15px;
  font-weight: 400;
  line-height: 1.4;

  atom-text-editor.editor .syntax--string.syntax--quoted,
  atom-text-editor.editor .syntax--string.syntax--regexp {
    -webkit-font-feature-settings: "liga" off, "calt" off;
  }
  
  .syntax--operator,
  .syntax--type.syntax--function.syntax--arrow,
  .syntax--punctuation.syntax--comment {
    font-family: "Fira Code";
  }

  .syntax--entity.syntax--other.syntax--attribute-name,
  .syntax--type.syntax--function,
  .syntax--storage.syntax--type.syntax--class,
  .syntax--type.syntax--var,
  .syntax--meta.syntax--parameters,
  .syntax--keyword.syntax--control,
  .syntax--modifier,
  .comment, .syntax--comment {
      font-family: "OperatorMono-MediumItalic";
      font-size: 1em;
  }

  .syntax--name.syntax--function,
  .syntax--variable.syntax--default,
  .syntax--name.syntax--class {
    font-weight: 600;
  }

}

Does not work with windows 10. Does with Operator Mono Medium

I tried a similar combo with Space Mono (free) and it is not working for JSX/React etc. Any Ideas? I think JSX is the Problem, because it looks nice on JS