13.4 definitely fixes the issue for me, for both existing and newly-created files. A video downloader I use happens to trigger it with the sort of files I download, so I have a large number of files with which to test.
Based on the description of what's fixed--an issue with non-ASCII filenames encoded in a particular way by certain software not opening when double-clicked in the Finder, but otherwise being fine--if you are still having issues, then it seems likely your problem is something different.
You said previously that you were having problems with files that don't have any non-ASCII characters (accents or non-English characters), which points to it being something similar but unrelated anyway. Even with the software I have that is 100% consistent in generating problematic files, if the file has no exotic characters in the name it was fine.
Questions to help narrow down:
Is it only Finder double-clicking and drag-and-drop that doesn't work? If you also can't open the file via the Open menu in the app, it's a different issue.
Does the workaround of editing the filename at all (hit return twice with the file selected is sufficient, even without changing it) fix the problem you're seeing? If so, then it presumably does still have to do with filename encoding; if not, it's something else.
You mentioned PDFs and Office; out of curiosity, is the full path to the files you're having trouble with very long? If the total of all folders and the filename in the path is over 250-some characters in length, some applications will choke and refuse to open files. Microsoft Word and Adobe Acrobat are notorious for this.