By dint of tinkering to find a solution, i've found to get round the problems is to use a series of commands:
1 - I rename the various folders containing the reverse proxy scripts with commands such as "mv /www/server/panel/vhost/apache/proxy/monnomdedomaine /www/server/panel/vhost/apache/proxy/XXXmonnomdedomaine", thereby inhibiting the reverse proxy.
2 - I run the command "/www/server/panel/pyenv/bin/python -u /www/server/panel/class/acme_v2.py --renew=1", this no longer causes any problems as the reverse proxy is now disabled.
3 - I rename the folders as before by doing a reverse command 'mv /www/server/panel/vhost/apache/proxy/XXXmonnomdedomaine /www/server/panel/vhost/apache/proxy/monnomdedomaine".
4 - I restart apache to make the proxy reverses work correctly with the command "/etc/init.d/httpd restart".
In summary :
echo "Start of script"
echo "The reverse proxy folders are renamed with XXX".
mv /www/server/panel/vhost/apache/proxy/mydomain /www/server/panel/vhost/apache/proxy/XXXmydomain
sleep 5
echo "We are renewing the certificates"
/www/server/panel/pyenv/bin/python -u /www/server/panel/class/acme_v2.py --renew=1
sleep 5
echo "We rename the reverse proxy folders without XXX"
mv /www/server/panel/vhost/apache/proxy/XXXmydomain /www/server/panel/vhost/apache/proxy/mydomain
sleep 5
echo "Apache is restarted to ensure that the proxy reverses are working properly".
/etc/init.d/httpd restart
sleep 5
echo "End of script"
I hope my solution helps someone!