I’m not sure if the original poster ever got this working, but I’d suggest trying to run it (consolewd and cronmysql) as root to rule out any local system permission issues. However, I’m running consolewd as a new basic user and the only special permissions I had to set were for access to the USB device. Everything is working fine, except the SQL part.
I’m also using Raspbian 9 and MariaDB 10.1.23. However, it’s not the access violation that’s my problem. It appears to not like MariaDB. I’ve tried the new cronmysql, from this thread, but the error is the same (only wanting version 5.6, instead of 5.5)
TMySQL56Connection can not work with the installed MySQL client version: Expected (5.6), got (10.1.23-MariaDB).
I can’t find any way of getting mysql 5.5 or 5.6 installed, and unfortunately I can’t spoof the MariaDB version in 10.1. It’s apparently a feature in 10.2, but 10.1 is the latest for Raspbian 9.4.
Are we able to get support for MariaDB, please? 
Hopefully it’s just a matter of accepting the name/version