It seems that [sway][keyboard / input setup] On sway reload: crash with “Lost connection to Wayland compositor” is no longer an issue. I’m not sure if it’s been resolved by yesterday’s sway 1.8 update, or today’s new Firefox version. I suspect that sway developers must have resolved it on their side, even if they claimed the issue to be on the FF side. They always say: “it’s not our bug”.
Anyway, I’m glad to see FF back on my machine.