🚀 go-pugleaf

Because FM's internal coding uses the hexcodes, not the ANSI ones.
Look at the FM Characters online manual and compare the hexcodes for
the Standard Character column to those in the Symbol/Dingbats column
for the same ANSI value.

When you copy & paste a Symbol encoded font, the ANSI value is
picked-up. What gets used in FM is the Standard character set hexcode
equivalent of the ANSI value (i.e. FM remaps the ANSI value to the
hexcode using the "Standard" table, not the "Symbol" table).

For example, if you copy the Symbol "arrowdblboth" at ANSI 219
(defined as \xdb in hex in the FM internals) and then paste that into
FM, it shows as � (Ucircumflex or hex \xf3, the hexcode for ANSI 219
in the "Standard" character set). If you then apply a character tag
for the Symbol font (naively thinking that you'll get the double-ended
arrow), you instead get "integraltp" at ANSI 243 (\xf3) in the FM
"Symbol" encoding. A real Hmmmm? moment. You have to look at the
hex-code values and ignore the ANSI numbers. So you think you're
copying a double-ended arrow, but end up with the upper half on
integral sign. Neat trick to blow one's mind.

That's why I recommend using the FM key sequences with the appropriate
font selected for the paratag or applied character tag.