The problem (window on right):
The 'fix' is basically shown in the output I put in the DIALOG window.
Even though you are correctly setting
NCURSES_NO_UTF8_ACS=1, you are setting the other Locale settings to something not support under terminal/console emulators like PUTTY. To work on as many as possible you should be using Unicode. You are not.
You are setting Locale to "C" (only).
If you wish to stay with 'C', you need to append ".UTF-8" to them:
# For perl and run-time locale setting. export LC_ALL=C.UTF-8 export LANG=C.UTF-8
LC_CTYPE is usually set by setting
LC_ALL, anyway, but LANG needs to be set directly.)