TNT's fuse is pretty much invisible, it looks too much like background, maybe just make the TNT a fuse-less block of alternating bars?
You could maybe make the exit look like stairs?
Making levels is hard with these wall tiles (and they look ugly right now, imo). A notable example would be Draknek's
Boxes Love Boxing Gloves. As you can see in the levels, all the walls are just '#', which is probably the main benefit.
This thing sounds like something interesting to be discovered and a puzzle in itself, so it's a potential spoiler (highlight it): It's not apparent that you recover from blowing yourself up and can still place bombs, is this intentional? Is this useful in some future level? Because that would sound pretty cool.
Finally, about the fire propagation: I'm not sure why you would want the FireDummy objects, they seem completely optional.
[Fire1Center] -> [Fire1CenterDummy] sfx1
late [Fire1CenterDummy] -> [Fire2Center]
is almost the same as
[Fire1Center] -> [Fire2Center] sfx1
because you never use the Dummy objects. Even if you would, you probably could just use Fire2Center instead instead of Fire1CenterDummy. The 'late' keyword isn't something you should even need in your game, because it's meant for executing commands after movement, which is just before the player sees the game rendered. This is useful when you want to, for example, trigger a pressure plate when the player pushes a crate on it, rather than the next turn. The computer does it like "Normal commands -> Movement -> Late commands" but the Movement part doesn't really change anything in your game.
Finally, why is the last level so visually confusing? It's all about pushing TNT but there's a tiny segment that you have to blow up for no reason and you're also given the ability to reload bombs, even though 2 is enough AND the level is named Run even though no running needs to be involved?