It definitely works with comma without space after it. I coped my own parameter from the one of the nodes:
However make sure to do not use a curly quotes: “ and ”, use only straight ones: ".
But I guess you want to exclude Europe-North-1 and US2, not Saltlake.
Please provide your parameter between two new lines with three backticks, like this:
```
storage2.trust.exclusions:
```