Sorry for the trouble with your conversions. As it happens, there are a few cases where the open source NRefactory engine doesn't well handle the VB to C# conversion. One of those cases is trying to add "()" to C# when they're missing in VB. Technically, VB could also have the "()", so it's hard for the converter to predicatively add these characters.
The other challenge the syntax converter has is converting parenthesis to brackets. I think it's because the conversion engine doesn't fully understand your code (since it's not trying to compile it), so it doesn't know if the parens in VB are method calls or indexers. In VB parens can be both; in C#, parens are only for methods, and brackets are only for indexers.
We'll investigate possible solutions to both issues, though. For now, expect to make some manual tweaks if your VB code covers either of these cases.