Here is another possible solution for you... I just started with LiveCode but have many years behind me with other developer languages.
I got tricked by my eyes, you see what you want to see...
Dev environment in this case: Win 10, MySQL 5.7 local install, followed standard config on this to test some stuff (most is "next-next-finish" installation).
Anyway, this is the code I got stuck on:
put revOpenDatabase("MySQL", tDatabaseAddress, tDatabaseName, tDatabaseUser, tDatabasePassword) into tResult
Got connection, but got "access denied 'myuser' on 'mydatabase'
Checked the connection through MySQL command line ( check this: Search online, I cannot post links it seams?), and that worked. Also in workbench the new user worked. Did a restart of the service and it did not help (did not expect it to do so, but had to try..).
THEN I ran a debug (should have done that in the first place).
In the debug window my variable tDatabasePassword = tDatabasePassword. Hmm.. why? The reason was an error in my variable section. In my variable declarations tDatabasePassword was now named tDatabasePasswordput (put at the end), because of a previous stupid typo / editing.
So.. based on this I can tell that livecode is not to picky on variable names when used and not declared properly. Sure this can be set in the IDE but I am not there yet.