Using Scheme with Sublime Text 3 I have a couple issues:
The package doesn’t recognize some file extensions, like *.sls, that are associated with different kinds of Scheme scripts, depending the RnRS version. I’d like to know how to associate such file extensions with the Scheme package, so I don’t have to do it manually every time I open one.
The package flags brackets, when used instead of parentheses, as erroneous red background. It’s very common for Scheme scripts to use  in some places instead of () for readability. Without getting into whether this makes Scheme code more readable (an arguable point), the fact the package makes brackets look hideous definitely hurts readability.
I looked at Scheme specific settings but they are aimed at overriding general text settings, and didn’t offer any specific settings that jumped out at me as addressing either issue.