Description of the new feature/enhancement (with images if possible)
Missing characters are shown in Courier as fallback, and some Cyrillic glyphs in Cascadia Code are formed through composites. You can refer to the Adobe Cyrillic 3 character set right here. This covers most of the basic Cyrillic block as well as some Cyrillic Supplement characters too, shown here
Description of the new feature/enhancement (with images if possible)
Missing characters are shown in Courier as fallback, and some Cyrillic glyphs in Cascadia Code are formed through composites. You can refer to the Adobe Cyrillic 3 character set right here. This covers most of the basic Cyrillic block as well as some Cyrillic Supplement characters too, shown here
Cyr. Supplement:![2022-07-20 15_30_58-BabelMap](https://user-images.githubusercontent.com/90877277/179923362-ccf99497-a8c6-4c58-ac92-b6c832a69557.png)
Also see #639.
Proposed technical implementation details (optional)
Many glyphs are formed by adding descenders or diacritics, most are copies of existing Cascadia glyphs, such as ำ and ำก.