Comment 13 for bug 1905105

I was able to simulate your issue on my system by explicitly setting the character encoding:

    $ PYTHONIOENCODING=ascii cubic

I got the same error as you did:

UnicodeEncodeError: 'ascii' codec can't encode character '\u2022' in position 2: ordinal not in range(128)

(1)
I wonder is a similar approach to explicitly set the encoding when running cubic would help with your situation?...

    $ PYTHONIOENCODING=utf8 cubic

(2)
To make testing your terminal easier, instead of running cubic each time, just cut and paste the following:

    $ echo -e "This is a UTF-8 bullet character: \\u2022"

It should output:

    "This is a UTF-8 bullet character: •"

(3)
Assuming the system defaults are set correctly...

    Can you create a new "terminal profile" in Xubuntu (like Gnome Terminal allows)?
    May be a "clean" terminal profile would help?

(4)
If the issue is due to your current logged-in environment...

    Could you create a new user on your system (with sudo privileges, of course)?
    May be a "clean" user without the legacy /home directory would help?