Just ran into an issue with http://www.codechanger.com/, where I had code calling Substring() and the converter started throwing errors about bad syntax.
I was finally able to narrow it down to the following test case:
It looks like its choking on the "Sub" part of it, thinking that it's the keyword, not part of a function name. If you lowercase the sub, as follows:
this works and translates fine (though, obviously it doesn't make valid C#).
Just wanted to make sure this was documented.