Can I replace filename and size label on the page after upload to a custom text?

uploadcare--widget__file-name and uploadcare--widget__file-size are CSS classes that need to be updated to achieve this. To modify their content, add the following to your stylesheets:

.uploadcare--widget__file-name:before {
  content: "Content for file name"; 
  visibility: visible;
}

.uploadcare--widget__file-name {
  visibility: hidden;
}

.uploadcare--widget__file-size:before {
  content: "Content for file size"; 
  visibility: visible;
}

.uploadcare--widget__file-size {
  visibility: hidden;
}