I don't think it's wise to have four parsers doing actually the same. <<
On the server side it seems that speed is a desired feature, so C or C++ seems to make sense as a preferred language. They also have the advantage of being very widely understood. Broad understanding probably favors C or simple C++ (simple C++ meaning without really fancy use of classes and inheritance). Hopefully either of those would allow a lot of people to get involved in optimizing and reusing the code.