Recent professional English VN releases from known good localization outfits (anything recent from MG, SP, and possibly JAST?) are universally higher quality than fan translation patches. The team that did Dies irae was not associated with any of those, and this was their first project; they likely incorrectly believed they didn't need (or perhaps could not afford at the rate they promised? who knows.) as much QC as is merited. Turns out that when you have hundreds of thousands of words to deal with (Dies irae might even be into the millions?), even if you're pretty damn good, you still make a lot of mistakes.
I'd be curious to see a citation of a really excellent fan translation, which some people in this thread seem to be asserting not only exists, but even go so far as to imply it's the norm. Honestly, even the best ones I've read have universally been filled with errors (at least as high an error rate as what you're seeing in Dies irae, given the number of lines you've quoted and the size of the script), and that's to say nothing of abominations like 11eyes. KoiRizo is a great example of a fairly well-written script, for a fan TL, which is again still chock-full of errors, because QC is both hard and hard to prioritize for fan TLs. Or we could go look at, I dunno, the Little Busters! fan TL, which doesn't even have word wrapping in the entire script. I've certainly never read a fan TL with as high a quality as the S;G0 release being called out in this thread, for instance, even though S;G0 does indeed have at least a couple dozen errors that I found when reading it. I think that's nonetheless still pretty solid for a script of its size.
I also don't even usually see fan TLs releasing patches; the aforementioned KoiRizo, for instance, certainly had someone who was willing and able to make all those fixes, but the people making the patches couldn't be bothered to take them.
Fan TL is a fine thing for getting exposure for stuff that otherwise wouldn't get it, but you're kidding yourselves if you genuinely believe it's higher quality than what you're getting from known good English VN publishers.