You may prefer to instead adopt the "Hyphen"-class approach from the linked documentation so that predictions extending from the - are possible; this would allow hyphens to still act like English hyphens if not attached to normal letters and words. I believe that "ALetter" is sufficient for your needs, though.
If this has unwanted side-effects or doesn’t cover everything you need regarding hyphens, things are likely to get pretty technical - the Unicode word-breaking spec isn’t exactly “light reading.” Feel free to reach back out for additional guidance if needed.