I guess others probably realised this but with regard to the log commands the default is actually * warning

Regarding the use of

[log]
to = logs/system.log.txt
level = * trace

and

level = * error

If you put both in it will use the last one eg

[log]
to = logs/system.log.txt
level = * trace
level = * error
If you add the level = * warning or have no level command then you get the errors + warning commands (although warnings are misleading as you get a lot of them anyway).