Trust me, Tasker flushes to disk a lot when editing globals, it was the LED flash that clued me as I used to use a for loop on a global array and each time it ran, the LED went mental.

That won't work, firstly, you will need to use sh -c inside su -c to pass commands like that. Secondly, single quotes in the script would definitely break quoting.

If it doesn't, then why am I using this method almost religiously and with no issues... I almost always store the template in a variable, adjust as needed. su for root -c Pass command to the shell with the -c option. sh doesn't need any options, escaping or flags to execute the variable script.