“Macabre” is “of unknown origin”. Could “macabre” be from Arabic “maqbara” for cemetery? I don’t know Arabic, but I know Hebrew, and the root q-b-r means “grave”/“bury”. Correspondingly, “m” is not part of the root of the Arabic word; i guess it’s the prefix denoting “place” or something like this. So maybe it’s unrelated after all. I know that superficial similarity is not enough to establish relation, but still, just curious.
A theory:
The danse macabre is related to the chasse macabée—one of the christianized and a gallicized version of the nordic Wild Hunt.
The chasse macabée (or chasse des Macabées) is an ancient legend from European folklore—particularly in France—that links the myth of the Wild Hunt to the figure of Judas Maccabeus and to medieval legends about the dead dancing or riding by night.
https://www.persee.fr/doc/roma_0035-8029_1958_num_79_316_3149
You could dig into timelines and historical contact between languages to try and gauge the likelihood of a relationship here. But if the primary etymological sources couldn’t establish an origin for this word, it will likely take some serious research into primary sources to try and find something definitive.