Oops I noticed this thread too late
I have a harl... she's very much puppy still, but we've never noticed any edginess with her or anything. She's just a big pile of love.
As far as hearing and vision goes, eyes/ears with no pigment on them tend to work less/fail totally as opposed to eyes/ears with pigment. While it's generally true that if one functions in some form, the other will as well, it's also very common to have a deaf dane that can see, or a blind dane that can hear. There are varying degrees of sight/hearing loss in poorly marked harlequins.
I'm sorry to hear it didn't work out for you, but I hope it does in the future