Here's a small example. If you run this in a Draw Event, you'll notice that the black words look correct, while the red ones only show a part of the word correctly. It seems that tj_encode() is to blame.
var obj = tj_object("salmão", "Cátia");
var xx = room_width/2;
var yy = 100;
draw_set_halign(fa_center);
draw_set_color(c_black);
draw_text(xx, yy, "salmão");
draw_text(xx, yy+50, "calças");
draw_text(xx, yy+100, "Nazaré");
draw_set_color(c_maroon);
draw_text(xx, yy+150, tj_encode("salmão"));
draw_text(xx, yy+200, tj_decode(tj_encode("salmão")));
draw_text(xx, yy+250, tj_decode(tj_encode("calças")));
draw_text(xx, yy+300, tj_decode(tj_encode("Nazaré")));
draw_set_color(c_green);
draw_text(xx, yy+350, tj_get(obj, "salmão"));
draw_text(xx, yy+400, tj_encode(obj));
By the way, I was able to circumvent the problem with that trick I mentioned, so I don't have any urgency in getting this fixed. Let me know if I can help further!
EDIT: I tested with some Japanese characters and they also disappeared. However, I tested tj_encode("вадим") and it displayed "2048<" with the quotes included.