Unicode Private Use Area (PUA) characters display as hex codes instead of symbols in OnlyOffice

[TFLR]

This issue is unique.

• I have used the search tool and did not find an issue describing my bug.

Operating System of DocumentServer

Linux (DEB package)

Version information

8.2.2-22

Expected Behavior

The PUA characters should render their corresponding glyphs or icons based on the selected font.

Actual Behavior

In the preview section of the "Insert Symbol" dialog, the PUA characters are displayed as hexadecimal Unicode codes (e.g., E06C) rather than their corresponding glyphs.
After selecting a character and inserting it into the document, the correct symbol is rendered in the document.

Reproduction Steps

1. Open OnlyOffice
2. Go to the "Insert Symbol" menu.
3. Select a font that supports PUA characters, such as Abyssinica SIL or Ubuntu Mono.
4. Choose the range Private Use Area (PUA).

Additional information

I have confirmed that the fonts used include PUA glyphs by testing them in other software (e.g., LibreOffice, Gucharmap).