Thanks for checking it out! The fuses not respecting the time-slow stuff is definitely not intentional.
Recently I attached a time-keeper to all my entitites basically that allows for localised time slowdown or speedup. Not every script is properly respecting the time-keepers at the moment, there are a few I created that base themselves off timestamps rather than an elapsed perception of time that I need to convert.
Yeah I hadn't noticed that extra wall suddenly appearing in my level until I tested it out on the WebGL version. I can see my editor right now and it isn't present so I'm not quite sure what the heck was going on there; potentially line-endings on the plain-text level file being interpreted into tile-height characters that are interpreted by the builder! Fancy that.