See https://github.com/executablebooks/rst-to-myst instead. https://github.com/readthedocs/recommonmark/issues/221

convert_recommonmark_to_myst.py

import json
import os
import re
import sys
from textwrap import dedent

tables_replacements = {
    '```eval_rst': '',
    '```': '',
}

eval_rst_replacements = {
    r'.. markdown *::': '',
    r'\.\. admonition:: Hint\n *:class: hint': '.. hint::',
    r'\.\. admonition:: Note\n *:class: note': '.. note::',
    r'\.\. admonition:: Tip\n *:class: tip': '.. tip::',
    r'\.\. admonition:: Warning\n *:class: warning': '.. warning::',
}


def tables(matchobj):
    content = matchobj.group(1)
    for old, new in tables_replacements.items():
        content = re.sub(old, new, content)

    index = 0
    lines = []
    for line in content.splitlines():
        line = line.strip()
        if line.startswith('=='):
            if index == 1:
                lines.append('-- | - | - | -- | - | -')
            index += 1
        elif line:
            line = f'{line:22}'
            lines.append(f'{line[0:2]} | {line[4:5]} | {line[8:9]} | {line[12:14]} | {line[16:17]} | {line[20:-1]}'.strip())

    table = '\n'.join(lines)

    return f'<div class="disclosure-timing" markdown=1>\n{table}\n</div>'


def eval_rst(matchobj):
    content = matchobj.group(1)
    for old, new in eval_rst_replacements.items():
        content = re.sub(old, new, content)

    contents = []
    for text in re.split(r'\n *(?=\.\.)', content)[1:]:
        text = text.strip()

        match = re.search(r'\A\.\. ([^:]+)::(.*)', text)
        directive = match.group(1).strip()
        arguments = match.group(2).strip()

        if directive == 'codelisttable':
            directive = 'csv-table'

        options = []
        body = []
        for line in dedent(text[match.end(0):]).splitlines():
            line = line.rstrip()
            if line.startswith(':'):
                options.append(line)
            else:
                body.append(line)

        options = '\n'.join(options)
        body = '\n'.join(body)

        if body.lstrip().startswith('{'):
            body = json.dumps(json.loads(body), ensure_ascii=False, indent=2)
        else:
            body = dedent(body).lstrip('\n')

        parts = [f'```{{{directive}}}']
        if arguments:
            parts.append(f' {arguments}')
        if options or body:
            parts.append('\n')
        if options:
            parts.append(f'{options}')
        if options and body:
            parts.append('\n\n')
        parts.append(f'{body}\n```')

        contents.append(''.join(parts))

    return '\n\n'.join(contents)


for root, dirs, files in os.walk(sys.argv[1]):
    for file in files:
        if not file.endswith('.md'):
            continue

        with open(os.path.join(root, file)) as f:
            content = f.read()

        content = re.sub(r'<div class="disclosure-timing">(.+?)</div>', tables, content, flags=re.DOTALL)
        content = re.sub(r'```(?:{eval-rst}|eval_rst)(.+?)```', eval_rst, content, flags=re.DOTALL)
        content = content.replace('\n\n\n', '\n\n')

        with open(os.path.join(root, file), 'w') as f:
            f.write(content)