Web extension converter fails to accept valid manifest keys

Hi, I'm using the web extension converter (aptly named safari-web-extension-converter 😄) to try to convert a Firefox- or Chromium-based extension to work on Safari. When I run the program, I get the following output:

Platform: macOS
Language: Swift
Warning: The following keys in your manifest.json are not supported by your current version of Safari. If these are critical to your extension, you should review your code to see if you need to make changes to support Safari:
	run_at
	browser_action
	webRequestBlocking
	version
	default_locale
	js
	matches
	manifest_version
	description
	options_ui
	<all_urls>
	scripts
	storage
	alarms
	webRequest
	web_accessible_resources
	name
	icons

Of course, this doesn't make any sense. According to https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json (sorry, the Dev forums won't let me make a hyperlink to Mozilla...LOL), these keys are indeed valid for manifest V2 and should be supported by Safari. The compatibility chart also explicitly shows Safari supporting these keys(/APIs). The Apple Developer Docs page also doesn't mention these keys as being unsupported. Ultimately there's really no reason for the converter to be saying these blatant lies...smh.

This error about unsupported manifest keys only brings up a few results on Google, as it seems this tool has been pretty neglected. As such, I suspect this is a problem with the converter.

Any help, etc. would be appreciated — thanks!