What your asking for is to decompile an .exe - as far as I know you can't do it, and shouldn't do it even if you could because it's illegal. If you need to recover your lost .mfa files I'd use something like: Please login to see this link.
I've been there and done it before when swapping to a new PC. You can recover your files it's just takes a bit of time yet it's worth it. Another tip is to always back up your files using a cloud service.
It's not illegal actually, but doing it for code that the IP right holder has not given permission for in most cases is. The Final Fantasy 8 remaster was built around reverse-engineering and/or decompilation, since the devs lost the original source code. And they even got a different, external team to do it for them. Because the rights holders had given them permission for that specific purpose. So what the original poster is requesting is not illegal, just...
...well, that I know of there isn't any tool currently that can decompile a modern Fusion game, due to decompilation measures being added in to prevent people from stealing code. Which, I should be clear, is a good thing to exist overall, even if inconvenient for this specific use case.
Most game makers, if not all game makers are concerned with keeping their code and hours of work safe from being ripped off or cloned. If decompling was readily available it wouldn't be very secure; everyones intellectrual property would be available to everyone. Here a previous post that explain it further Please login to see this link.
Minecraft mods are literally only a thing because of the devs actively letting people decompile its code under specific terms and conditions of what you're then allowed to actually use that code for.
....but they made those terms and conditions so people couldn't decompile the code and just do whatever with it in any case. But it does all the same allow decompilation, just with specific terms.
Also, I just checked the Runtime Agreement, and "reverse engineer" and "decompile" don't show up anywhere in it. Clickteam Fusion 2.5's license agreement, however, prohibits reverse engineering Clickteam Fusion 2.5 itself, which is what the person who made that thread was probably thinking of.
It's also not true that decompilation would inherently make everyone's intellectual property available to everyone. Since it still wouldn't be legal to use it for other people's games without explicitly being given permission to do so from the rights holders, and you could very much get caught and arrested and/or fined for stealing such code. And, interestingly enough, decompilation tools being used on the allegedly stolen code would be one of the easier ways to try to point out the code was stolen to begin with, though you'd probably have to like, get some kind of warrant or something first to do such a thing, since otherwise if the code wasn't stolen, well, that'd make the person making the accusation the ones stealing code now.
That and it's not like games in other engines are hard to decompile. Actually that's one of the advantages Fusion has, it's kinda harder to decompile games made in it even without the dev first manually using a code obfuscator.
And yet, thus far, it has not led to this proposed issue of everyone's intellectual property being available to everyone.
...all the same though, rambling about inaccuracies about legality aside that frankly aren't even relevant to the core of the answer I have here so much as to set the record straight for the person who started the thread...
The tl;dr version is, there isn't really a working decompiler for the latest versions of Fusion as far as I'm aware.
