I tested with the example you posted:
1. create a text file with file name and content with
the problematic chars
2. execute file command on the file
e.g
file ~/охлюви.txt
охлюви.txt: Unicode text, UTF-8 text, with very long lines (485)
Let us see what is the output
but I don't have any issues with cyrillic fonts, here is the output:
a@scatorcio:~/Scaricati$ file ~/Scaricati/охлюви.txt
/home/a/Scaricati/охлюви.txt: ASCII text
a@scatorcio:~/Scaricati$
I also correctly see cyrillic text displayed in the applications where I don't see
"𝘙𝘪𝘰𝘮𝘢" displayed.