Eh, A lot of modern terminal emulators don't seem to bother providing termcap/info entries, or setting their own $TERM variables. In reality, most code just fires off ANSI sequences and hopes for the best. Looking quickly at the source for Hexyl, I think that's what the ansi_term library it uses does.

If anything, I've found doing this works better then trying to muck around with ncurses, which often gets actively mislead by incorrect terminfo entries.