I am from Norway. As a Norwegian, I need the additional Norwegian characters when I write Norwegian (e.g. comments are often written in Norwegian when programming). The characters in question are "æøå" and "ÆØÅ" (lower case and upper case, respectively).
Consequently, every language definition in my installation have the following definition of characters being part of a word:
Tools --> Options --> Languages --> <pick-your-language, e.g. Bourne Shell> --> Word Chars: "a-zA-Z0-9æøåÆØÅ_"
Still, if any of the characters æøåÆØÅ are encountered, the cursor stops in the middle of a word when moving the cursor (typing <Ctrl>+<RightArrow>) as if it was a word break.
This actually worked properly in the 2014 to 2019 editions, so I haven't experimented by changing the Word chars content, except for moving "_" to the very end, and it stopped working in the 2020 edition. Now it seems it is going to be carried over into 2021. I hope it will not.

(2014 was my first SlickEdit edition. I am and always have been using Brief emulation with SlickEdit).
Also:
So far in the beta, I have only tested the Linux variant, but this problem is also valid for both Linux and Windows 64 bit of the 2020 Pro edition (no surprise there - Slick-C OS isolation ...).