Unfortunately, All major languages are supported in all features, including notes, Except on reports where we know some languages do not display correctly during the session. (ie: chinese).
The two largest groups of languages are UTF-8 and UTF-16: those that can be represented with 8 bytes of memory (UTF-8) and those that require more memory and 16 bytes: UTF-16.
Nearpod works based on UTF-8.
Most languages -including western ones- fit within 8 bytes.
Some major languages that do not are: some forms of Chinese, Japanese, some Thai dialects, Indian dialects and Russian.
That is why it appears as "???" the platform is not able to read those characters.