When using the item replace command, I’d like it to replace the item in a trinket slot. The names of the slots don’t seem to work. Is this a bug or are there special names in the commands?

Did you figure it out? I also try to find working slot id.

it should, in theory, be something like trinkets.chest.necklace for the necklace spot. i'm not sure if this has been implemented.

There is a new /trinkets command added in the latest release for this function