Thanks everyone. I'm using Charles's Saktumiva, and the convention there (as Charles pointed out to me; I should RTFM) is to use the broken pipe character, "¦". So that's what I'm doing now.

For my purposes, I do need to distinguish this char from a daṇḍa, because it's functionally different, and because I want it to show up in my apparatus in places where I don't want the daṇḍa to show up. It's even written slightly differently in some MSS, with a little bottom-serif/flourish.

Like Patrick, I don't see a word-separation function in my MSS usage. It's really a line-filler or Randausgleich "margin-equalizer". So is a hyphen, though. So is there any good reason not to think of these as hyphens? NB hyphenation practices differ greatly between languages and even between UK and USA English, so the fact that these line-fillers are not being used as etymologically-determined word- or syllable-separators isn't a reason not to call them hyphens.

Best,

Dominik