I think it depends on the interface provided.
If there are any conversations implemented then you might be free using any other language.
Talking about FS, any Language beeing part of "Visual Studio" works, BUT there are some preferences that make life easier.
At least taking that FS-SDKs into concern, most of them life from XML and are not that easily to be accessed in other ways.
OK, if your program generates that xml and then gets it compiled by any FS compiler, thats a different question.
Then you are free to use what ever language you might decide.
There are other areas in FS where you are better off in executable code programming, e.g. Gauges, my personal thinking.
What ever language you select it needs to represent the FS-demandments.
Sometimes strange to meet, these xxx.h files at least seem to implement the Cxxxxx behavior, from C, C++, C#, what ever. If you are using Visual C#, you never might have any problems, as it integrates from the point of objects or objects implementation, now not complaining about the correct wording, best into what ever MS-Code, including Silver.