Home row mods M-S-], C-M-<Backspace> missing?

[brosasaki]

After setting up home row modifiers keys via e.g. C/a (tap-hold-next-release 200 a lctl), KMonad works excellently!
Save for one issue: M-S-] (AKA Gui-Shift-], Command-}, Super-}, etc.), in particular when using the left home-row-mods, does not pass through, despite the normal right modifiers, left modifiers, and right home-row-mods working perfectly with it. I've checked sudo kmonad config.kbd -l debug and the log shows KMonad recognizing the meta and shift layers from the home row mods and all other keys except for ]; debug simply doesn't output anything at all upon press. I've looked my config up and down, but the odd, asymmetrical nature of the issue makes me suspect that it's a KMonad issue, and not a config or Firefox (which uses Command-Shift-] for moving right one tab) issue.
My system is a MacBook Pro 12,1 running macOS Monterey 12.6.8, and I am using the vosaica/kmonad branch and dext version 2.1.0 according to amiorin's guide. It appears that the fork has been merged, but I couldn't get kmonad/kmonad to work with a dext 2.1.0 from a Karabiner-Elements install (now removed) and the documentation doesn't reflect the merged branch; LMK if there is a way to use the features from vosaica/kmonad in the main branch, and I can try and make a PR for the documentation.
Here's my config, for good measure:

;; See keymap/tutorial.kbd for a more complete tutorial

#|
(deflayer template
  _    _    _    _    _    _    _    _    _    _    _    _    _   
  _    _    _    _    _    _    _    _    _    _    _    _    _    _
  _    _    _    _    _    _    _    _    _    _    _    _    _    _
  _    _    _    _    _    _    _    _    _    _    _    _    _
  _    _    _    _    _    _    _    _    _    _    _    _    _
  _    _    _    _              _              _    _    _    _    _   )

|#

;;;; Setup
(defcfg
  input (iokit-name "Apple Internal Keyboard / Trackpad")
  output (kext) ;; shouldn't this be called "dext" now?
  fallthrough true
  allow-cmd true)

(defsrc
  esc  f1   f2   f3   f4   f5   f6   f7   f8   f9   f10  f11  f12
  grv  1    2    3    4    5    6    7    8    9    0    -    =    bspc
  tab  q    w    e    r    t    y    u    i    o    p    [    ]    \
  caps a    s    d    f    g    h    j    k    l    ;    '    ret
  lsft z    x    c    v    b    n    m    ,    .    /    rsft up
  fn   lctl lalt lmet           spc            rmet ralt left down rght)

;;;; Configuration
;;;;; Base layer
(deflayer default
  _    brdn brup mctl lp   bldn blup prev pp   next mute vold volu
  _    _    _    _    _    _    _    _    _    _    _    _    _    _
  _    _    _    _    _    _    _    _    _    _    _    _    _    _
  _    @C/a @A/s @M/d @S/f _    _    @S/j @M/k @A/l @C/; _    _
  _    _    _    _    _    _    _    _    _    _    _    _    _
  @Y   _    _    _              _              _    _    _    _    _   )

(defalias fn
  ;; Below, I use `around' to compose `layer-toggle' with `fn' (instead
  ;; of using `layer-toggle' directly) so that the `fn' keypress
  ;; actually gets emitted. This matters when using an application that
  ;; can use `fn' as a modifier (like Emacs).
  (around (layer-toggle yabaifocus)
	  (around (layer-toggle function)
		  fn)))

(deflayer function
  _    f1   f2   f3   f4   f5   f6   f7   f8   f9   f10  f11  f12
  _    _    _    _    _    _    _    _    _    _    _    _    _    _
  _    _    _    _    _    _    _    _    _    _    _    _    _    _
  _    _    _    _    _    _    _    _    _    _    _    _    _
  _    _    _    _    _    _    _    _    _    _    _    _    _
  _    _    _    _              _              _    _    _    _    _   )

;;;;; Home row mods
(defalias ;; home row aliases
  ;; KMonad calls gui-key “meta”; Emacs calls it “super”
  C/a (tap-hold-next-release 200 a lctl)
  A/s (tap-hold-next-release 200 s lalt)
  M/d (tap-hold-next-release 200 d lmet)
  S/f (tap-hold-next-release 200 f lsft)
  S/j (tap-hold-next-release 200 j rsft)
  M/k (tap-hold-next-release 200 k rmet)
  A/l (tap-hold-next-release 200 l lalt)
  C/; (tap-hold-next-release 200 ; rctl))

(deflayer homerowmods
  _    _    _    _    _    _    _    _    _    _    _    _    _
  _    _    _    _    _    _    _    _    _    _    _    _    _    _
  _    _    _    _    _    _    _    _    _    _    _    _    _    _
  _    @C/a @A/s @M/d @S/f _    _    @S/j @M/k @A/l @C/; _    _
  _    _    _    _    _    _    _    _    _    _    _    _    _
  _    _    _    _              _              _    _    _    _    _   )

...

Edit: C-M-Backspace (aka control-alt-backspace, control-option-backspace) also suffers from a similar issue. I've heard this is a low-level "restart" command in GNU/Linux; do the missing key combos have something to do with that?