For mummified binary dependencies, C# allows tediously fine control over stack frames in DLL function calls, and similar FFI systems are likely to be equally malleable; there's probably a blind spot towards reverse engineering in C++, due to the expectation that a random ABI should "just work".
The problem is actually not ABI, it's ODR violation. You can make it work, just make your own wrapper in C ABI, link it with whatever dependency (and version) that your vendor insists on, then `-fvisibility=hidden` and partial link the entire shit to avoid ODR violation.
People reverse these SDK partly because it makes the codebase saner, and partly because, well, this is trading, a saner implementation is almost guaranteed to be faster than vendor's bullshit one, and guess who cares about being a little bit faster than everyone else?