I looked to (info "(elisp)Key Binding Conventions") and (info "(elisp)Keymaps and Minor Modes") and (info "(elisp)Major Mode Conventions") and didn't found any restriction to use H- and s- modifier in modes.
I heavily relay on s- (super) key as user customization and recently found that in Magit:
commit 29ff1ec6a0f65caf5c9c5bf4869015946f12f7aa
Author: Jonas Bernoulli <jonas@bernoul.li>
Date: 2016-09-07 17:42:25 +0200
magit-mode-map: bind S-tab to magit-section-cycle-global
It appears this was always the intention. Keep the bindings
for s-tab and backtab, in case someone actually uses those.
I think it is illegal to define any H- or s- key binding as that can surprise users.
Are super and hyper key modifier permitted in major/minor modes?
BTW I opened issue: https://github.com/magit/magit/issues/3195