@outlandos: what about trying
this method I posted yesterday on the Firmware 3.16.0 thread ?
First, since the hyphen algo is supposed corrected in 3.16.0, (and if I were you), I should try to update the hyphen dictionary inside the kobo by adding the one of openoffice (link and method in the post linked). If it continues to not working, I should use the other method and not using the hyphen algo of kobo at all but use calibre + kobo_extra.css to hyphenate correctly the books.
Do you use calibre to send books into your gloHD ? If it’s the case, with KoboTouch plugin or KoboTouchExtended ? Hence, do you read epubs or kepubs ?