Apparently, using tilde-delimited code blocks within a list seems to work ok:
![geany-md-code-in-list](https://user-images.githubusercontent.com/1738281/115321945-925aad00-a14a-11...)
Just for the reference, the Scintilla's Markdown lexer: [`geany/scintilla/lexers/LexMarkdown.cxx`](https://github.com/geany/geany/blob/26f4813f0fad0c377c4698e28b0912afac7950a8...)