No, they should work. What happens if you try to look at them with the in-game menu option? You mean while I'm playing the game? It works fine then. If I load a previously saved game, however, the in-game transcript is empty. I don't know if that's how it normally is, I haven't played GF in over a ...

When playing Grim Fandango with ResidualVM, is there any way to read the grimdialog.htm files generated with saved games?

They only seem to contain gibberish. Is this a currently unsupported feature?