I tried installing both your convert-websters and
https://github.com/mortenjust/webster-mac linked elsewhere in this thread, and I think I prefer the other one, webster-mac. It is almost the same as yours, but its font size is more similar to the font size of the built-in dictionary, and it displays words as lower-case (though they are still listed in upper-case). Even though the webster-mac version improperly renders proper nouns as lower-case, I think that is a better tradeoff given that I know that I shouldn’t depend on the dictionary for capitalization, as lower-case letters make terms easier to read.
However, I don’t think I’ll be setting webster-mac as my default dictionary. macOS’s built-in New Oxford American Dictionary may have less colorful descriptions of the words, but it has features that greatly enhance readability that neither version of Webster’s has:
• Quotes are visually distinguished from definitions.
• The font size is consistent with other dictionaries.
• It describes pronunciation for each word (supporting two formats: diacritical or IPA).
• The correct capitalization of every word is demonstrated, both in the entry and in the index.
• It uses proper typography, avoiding fake dashes “--”.