The main issue I needed FTFY for, was because French characters got mangled using webcrack.
What I found was that Control + Underscore (Ctrl + _) characters or the ascii character called Unit Separator (US), seemed to get stripped during the process. I was also using webcrack, to unminify source code, which is why I needed to use FTFY however. So if I can use FTFY on code, you have to know it is a super helpful program.
Here was my invocation:
ftfy -g reactApp-badChars.js -o reactApp.js.fixt
If you assign it to me and I have time, will fix.