I forgot to say that if you want to reset to 0 the variable LETSENCRYPT_FAIL_COUNT for all your web and mail domains, you can use this command line:
for i in $(grep -rlE "LETSENCRYPT_FAIL_COUNT='[1-9][0-9]?'" /usr/local/hestia/data/users/); do sed -i "s/LETSENCRYPT_FAIL_COUNT='[1-9][0-9]*'/LETSENCRYPT_FAIL_COUNT='0'/" "$i";done
But don’t reset the count until you fix the root cause or you’ll have issues reaching Let’s Encrypt rate limits.