Hello. For many years (I have been using Tixati since 2011) there has been a problem with some unicode characters.

The most typical (screenshot):

https://cdn-thumbs.imagevenue.com/1c/a6/49/ME15G6N3_t.jpg

Tixati does not recognize for example U + 223C (?) as a result, it is impossible to hash the original torrent.

What OS and what version of tixati?
put a magnet link to that torrent here so that the mod can send it to the devs.

"What OS and what version of tixati?"
Any operating system and any version of Tixati. I've been seeing the problem for many years now.

"put a magnet link to that torrent here so that the mod can send it to the devs."
Any torrent containing characters like U+223C etc.

(magnetlink removed by mod and sent to devs)

The Unicode problems you are referring to were fixed recently, within the past two years.

The problem in your screenshot has nothing to do with that old problem with display of unicode chars.  That works perfectly now.

The issue is that Tixati sanitizes file names that begin with ~ because that is what linux systems use to denote a hidden file.  They don't show up in the file explorer.  So it changes any leading ~ in names to an underscore.  That is what the screenshot is showing.

To "fix" this would require splitting up the file name sanitizer to have a windows version and a linux version, but then you end up with problems with portable-mode if it travels between the two.

The issue is that Tixati sanitizes file names that begin with ~ because that is what linux systems use to denote a hidden file.  They don't show up in the file explorer.
This is wrong, tilde ~ is only used as a special character by the shell ("the textual console" for you non-techies) as a shortcut for the user's home directory. The hidden file is ".dotname" and that's nothing bad either. (this is the first time I've heard about ~ being used for anything else)
KDE's file explorer (Dolphin) allows you to create a ~name but it shows a fair warning:
If we are to be pedantic yet accurate, you can use ANY character except \0 (null) and / (forward slash) as a folder or file name.

On the other hand, tilde could lead to problems if used on Windows improperly (the short 8dot3 format) but Tixati isn't susceptible to this. Still, Windows disallows more characters in file names and I think these cases should not be blocked (during creation) but warned about like Dolphin does on Linux.