Hi,
According to https://www.swig.org/Release/CHANGES.current , the signature of SWIG_Python_AppendOutput changed in 4.3 which causes a siconos compilation error. They suggest to use SWIG_AppendOutput instead, which has the same signature of the old version of SWIG_Python_AppendOutput (not sure if SWIG_AppendOutput is available in old SWIGs though).