I have ledmap1.json and ledmap2.json and it still does not show on when I select in the drop down box at the bottom of the sequence panel . It does show correctly in the preset dialog box when I edit. But it is not in the API.
Referring to your picture of the Ledmap dropdown box, it looks similar to mine minus the Spiral_map_16x32. But when I select ledmap1.json, the drop down box will still show Unchanged.
You will need to use MM fork if you need ledmap ID returned in API calls.
Currently selected ledmap is not stored in any variable (in AC fork, to reduce memory footprint) and so not available in API calls. It is only possible to set ledmap, not retrieve it.