The shortcuts seem to be defined in gui/tex-table/tex-table.rkt. They look to be correctly defined, my guess is that \longrightarrow and friends are being mangled somewhere else. I’m not familiar enough with the code to know for sure where, but my guess is somewhere in gui/gui-lib/framework/private/keymap-global.rkt. I can try to figure out what’s going on myself, but it might be better if someone more familiar with everything could at least take a look.