When filtering by Light, some color schemes come through that are Dark. Is this a bug or do those color schemes have both light and dark versions? I looked at one of the dark "light" schemes and it didn't seem to have a light version on the github page.
I agree many of the default Vim syntax highlighting files leave a lot to be desired. You can improve it though and Vim highlighting is actually very powerful. I use a C syntax highlighting improvement plugin to add (among other things) highlighting to operators and function names in calls[1].
You can also quite easily customise syntax highlighting by placing your own additional syntax file in .vim/after/syntax for a language. I use this to add some more custom keywords. You could quite easily add highlight support for ".Else" in an after/syntax file.