Hey so the CMD+/ shortcut does not work in my keyboard layout: Swedish/Finnish layout, macOS.
Here’s why: the “/” character in this layout is SHIFT+7. Pressing CMD+SHIFT+7 triggers the “Help” menubar item in Chrome and Firefox. In Safari it does nothing.
Any keyboard shortcuts involving slashes, brackets etc. are likely to fail in many non-US keyboard layouts since they’re also often behind shortcuts like the above. Another example would be Sublime’s CMD+ indent/unindent shortcuts:  in this layout are under ALT+89. (I don’t know if these should or shouldn’t work in Glitch, since tab/shift+tab works fine.)
I’ve run into this exact same issue in the past when trying out early releases of new code editors. The solution has always been adding fully customizable keyboard shortcuts, but I’m guessing that’s already on your roadmap.
Meanwhile, is there any chance this could be temp-fixed somehow? Unless there’s already a hidden alternative shortcut I’m missing, this issue should be affecting nearly every Finnish and Swedish user. :S
Keep up the good work!