Some fonts may require additional configuration to display properly, so usually manual installation should be avoided.

Please run (and post the result here) fc-match sans and fc-match serif to check fontconfig picks wrong italic font. If that’s the case, try to remove the TTF files you’ve installed via the font manager you’re using, then install the fonts via the package manager - it should configures fonts properly.

The SCHEMA:PATH part seems slightly wrong (singular vs. plural). Try:

schema=org.gnome.settings-daemon.plugins.media-keys.custom-keybinding
path=/org/gnome/settings-daemon/plugins/media-keys/custom-keybindings/custom1/

gsettings get "${schema}:${path}" binding
gsettings get "${schema}:${path}" command
gsettings get "${schema}:${path}" name

I’d write a bookmarklet for that case:

javascript:
{
const name = 'ABC';
const d = new Date();
const year = d.getFullYear();
const month = d.getMonth();
const date = d.getDate();
document.activeElement.value = `${year}/${month}/${date} ${name}`;
void 0;
}

This bookmarklet inserts the desired text into the currently focused text box. Tested on Lemmy Web UI.

What program are you using to write or edit the comments?

As already suggested, take a look at i3 Window Manager’s docs: https://i3wm.org/docs/userguide.html because Sway (works on Wayland) is a port of i3 (works on X11).