Special chars can be entered by Unicode code points. How this works is described here:

https://en.wikipedia.org/wiki/Alt_code

In short words:
On windows: press and hold ALT, then enter the Unicode codepoint of the character in Decimal (NOT Hexadecimal) with leading zero.

On Linux and Mac and Chrome Book (i.e. Unix systems): Press and release CTRL+SHIFT+U, then enter the hexadecmial (NOT decimal) codepoint, then press ENTER.

However: I have tested it in the editor, and this works unfortunately only partially correctly: Under Windows with ALT it works, however the TrackChanges mechanism is not triggered, i.e. such a character is not marked as a change or only if another "normal" character was already entered before.

The combination under Unix systems unfortunately does not work at all, because ENTER is programmed to insert a soft line break in the segment.

We would have to fix both. Also, we would put instructions in the keyboard shortcuts section of translate5 (linked behind the question mark in the editor).