OP, why mess with acme.sh's cron schedule with your own cron job that calls its cron job? You might instead consider running acme.sh again with the "--install-cert" flag, coupled with its "--reloadcmd" flag, in order to automatically have it do the cert+key copying and nginx reloading for you when it renews:
acme.sh --install-cert -d grafana.tuxnet.dev --key-file /etc/ssl/private/grafana.tuxnet.dev.key --fullchain-file /etc/ssl/certs/grafana.tuxnet.dev.crt --reloadcmd "systemctl reload nginx"
Then you can ditch your custom cron and let acme handle everything on its own, as intended.