It's telling that the UTF-16 representation of the input is 00 FC, and the
UTF-8 representation of the output is 7C.
I think that line sysutils.c line 1001:
inbuf = ans; inb = strlen(inbuf);
inbuf = ans; inb = LENGTH(x);
like the analogous line in do_iconv (https://github.com/wch/r-source/blob/trunk/src/main/sysutils.c#L680 ).
More info: https://github.com/juliasilge/tidytext/issues/80
Even more info:
And a work-around implementation for translateCharUTF8: