However, the following countermeasure made be wonder:
> Manually retype excerpts to avoid invisible characters and homoglyphs.
Isn't this something you can automate? We should create linters for plain text (rather than code)? For example, depending on the language, reduce the text to a certain set of characters. Every character not in this whitelist is either replaced, or causes an error message the user (journalist) needs to deal with (i.e. remove it, or replace it with an innocent alternative, perhaps even proposing this replacement back to the linter project).
Of course, there are multiple ways for linting, which might become a fingerprint on it own. But then, if there are only 3 or 4 of such linter styles actually used (ideally, standardize on exactly one linting style), you can only tell which linter was used by the journalist, without any information about their source.