...

vf_replace_z; save_vf := f; f := vf_i_fnts[vf_default_font[save_vf]]; + if not font_used[f] then + pdf_init_font(f); save_v := cur_v; save_h := cur_h; w := 0; x := 0; y := 0; z := 0;

Is that a typo of font_used(f) ? I didn't yet try in pdfTeX, but tried and failed in luaTeX ( succeeded by changing font_used[f] ---> font_used(f) ).

Sorry, I've noticed that luaTeX and pdfTeX is different! Thanks, Akira