Unlike converting JPG to PNG, there is no commercial market for xmcd tools. However, this does not mean conversion is impossible. Because the xmcd format is well-documented (plain text or simple binary), the conversion is usually done via:
She fed the file.
MCD (legacy/plain-text)
First, open one .mcd file in a text editor (Notepad++ or VS Code). If it looks like readable text with # xmcd headers, you have a text-based file. If it has garbled symbols, it is binary (older version). Most are text.