I believe Unicode support was improved in this (6.1) release
Re:A new release for GNU Octave
by BlueTemplar on Monday January 04, 2021 @05:29AM
(#25629587)
Yes, it's mentioned in the review, but there are no details given. I doubt that Octave suddenly started supporting either of those features.
However, its lack of support for Unicode variables and filenames is very frustrating in this day and age…
(I understand that they are being stuck due to Matlab having poor support too.)