Just on a skim this looks fine, but it's a headache to implement to test. If I switch over to placeholders, either I have to duplicate the code to continue to account for the 2.0 files or I'm back to only being able to display English.

We should try and hurry this revision along after adding, perhaps not taking up any additional issues, so we can deprecate 2.0 and get the translations updated.

One issue I noticed that's not directly covered here is the certifier's report. The algorithm says to replace the entire string with a hyperlink, but the examples in the guidelines show only the words "certifier's report" hyperlinked. The guidelines approach makes more sense, but is there a way to accommodate that with a placeholder since it's not possible to know what words to hyperlink in any other language.
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It's similar to these placeholders, especially the email link, except instead of replacing with a variable value we want the marked text hyperlinked. Maybe something other than braces would work to identify the linkable text, like brackets?

(edit: changed last sentence from suggesting percent sign to bracket since we are using braces.)

I've finished implementing this now. The only other slightly tangential comment I have is that maybe we should say something about localizing the date, not just to replace the placeholder with whatever value you get from the metadata. No matter the language it may need some processing, if not to turn the date into the local language then to process out an attached time.

It could just go in the variable setup description, but it's a unique case of localizing the publisher data.