By convention it should return a bool as to whether or not it was compiled as all TryParse methods I can think of return a bool.
You could have two overrides one that provides errors and one that doesn't
bool result = Razor.TryParse(code, out textResult, out errors);
bool result = Razor.TryParse(code, out textResult);
The idea sounds ok, but I think a try/catch/finally would probably be better suited and it's not hard to add. We'll have to get the next version of the RazorEngine out first because there are major changes coming.