i was able to visually "fix" a mis-encoded tf2chan fic using word's "find and replace" and a UTF-8 debugging chart, creating an offline copy that visually matches what it "should" look like, but it's not a fool-proof process (for example, you have to be very sure to go in order from LONGEST present mojibakes to shortest, or you will not get the right result) and it kind of takes a while. unfortunately there is literally no better way to be doing this from the user end from what i understand, but at least the result is clean.
I might try doing this with other fics for my own enjoyment, but I want to tell others how to do it too, especially for archival.
before:
and after:
the cheat sheet is here. for each instance of mojibake put the "actual" in the "find" box, and "expected" in the "replace with" box, and hit "replace all". Again, make sure to go from LONGEST to SHORTEST. first 3 character mojibakes, then 2 character, then if present 1 character. do not go out of order. If something seems off, like if it found and replaced way more end quotes than start quotes, you went out of order.