Yeah, but I as you said ShiftWheel ins't really that universal 
, so you don't get those horizontal scroll messages by default from ShiftWheel (hence the feature request for Opus to handle vertical messages with Shift as horizontal ones just like many other apps do, and then you can also set decent scrolling speed with acceleration etc. (see below)
I've also tested passing horizontal messages on ShiftWheel with Autohotkey via SendMessage(0x114, 0, 0, FocusedControl, "A") (where FocusedControl := ControlGetFocus("A")), but then it's atrociously slow, had to add a Loop to make it faster (the horizontal scroll isn't even wide enough to scroll past 1 (one!!!) character, that's smaller than the minimum vertical scroll of 1 line), but then loops aren't as responsive, e.g., I can't change directions on a whim, there is some delay before the loop is done, so the best solution was to send Shift+←/→ keybinds instead — this is fast enough, but then scroll "on hover" doesn't work
At the moment I have the default Microsoft HID ones 10.0.19041.1 from 21.06.2006 and a generic bluetooh Logitech mouse (without SetPoint running)