@Christoph-Hart
Okay, this variant works at least with the test project. However, I had to use a timer instead of the panel loading callback.
Please note: You must set the default values using ScriptModulationMatrix.setMatrixModulationProperties(var newProperties), otherwise the modulation will be loaded as undefined for the mode if no user preset is loaded. I did that in the snippet as well.
Here is the snippet for anyone who wants to use the new modulation system in their plug-in:
HiseSnippet 2921.3oc6Zz0baabDTRHwT1wwtIoIsOggSefNQgCAHonTxzX9knLiEknDosiblNom.NRhHf6X..kkRFOSl9T+AzW6uj9P8OgNSlIOmeB8eP6d2ABbfjxlVwenjI3Aad6d6c6t2t29woNdTSruO0SI0p8NaDVI00T6dFIXX8gHahRqFJotgpK0ZrCJvlR5g8CTpc1HjuO1RIUpk2lMqToWQg+8eucMjChXhiAonbepsIdGaW6fXncpbWaGmlHKbOaWoYWrRKSJoN0gNF3nkUyqLBYdLZ.dWDaZKopbGj+PkTenZ9hlnML5WpPgM2rbIqivl80wGU1DkuDpeID.sHpXI8hJodisrrCndcCPAXekTqTiZcV2gzGQDav8s8sOxAyFnqzE1YA3lTGKlHxfpTensiUmIpJeEXQ6Dq3VVn3dW011V1QvkUfLDZwTHq.SsTR1a4DrmtL6kWh8lCKkRhkVQvR2Tsqom8nfXLL94ppsHAXu9H3bRlUDyUYoeTUsNElAIHmK5XbSOXPDEYWOe90zf+4Ve5pqBmU9AZttZ+YssHCrI3bldXPNZGYvzFE3YeZ1La2tdFfBW2b93.X0IXSF55HGmifS3rfI1rPi2BKbezXGlbLB6EXi8gc76VMcltXGfDDnf5BVLfLl4SzB7FiWCv0PPSKhcv8QNiY3VMMPT5L0GGP62GXxLeBab5LvOw.kYpYOh5f7xrFGJSlI91AmAnzykODn+tTOWji82hsB2L.9iYHgcLXLAOm0sqIxAeAV0U4KblCPjA3XYGlvzhg.PKxnwA7IGBIcFWaB7ai7S1HWzo7wvWzdSNAVW991G43iEP8Cvi5BrC.ElYjHt23fo1ivsHb4B2fPAatq84sztgJqld3uYLlXdFWgk4d9Xv8oCETYfoQU+Gh8nSVtPczpOFLTDlVB6sX6uXsV1YrghMuFQb.RZfBPfc0Da+ALCU2QTBLHal3ojQxxmZsCEYwtCyaZe.Nv8N5qA6yrLKeooxXT9OjM+ivJY86gGLYOvVvFje50I.4IVork3NjqZSb.VPq+XB2SRat9UY84NKqoAjCR4ZZOB4W0B1hasJbh5PAqUMWthLTk7crCGtrCmOY.sc5Xz4bizbvQP.sFxGudQlHmNVmwjXtSX1XBgY734ywynJxxYL69YiTF2R3JGLz1GzBzQBk.aSS6AdgdjOkYWjlSjsObU.rGVYkXnASXnaMQ.tErloAQnuG0MTHd5y+SYqu7wiNShhDDJYWZ.dOhf4ALZSipe+4hiY.5QcbXBzbPGJpmOgYIicOB6sl1ILFNZhPTgjgZTO+PMxQBME9CRSjRXWpt2HL47hOpD5DAgkVNjqfeEvCJc8vfRccrsvdJ1PrmqnJtKSgywQoC72+gJJKD0hKdmhZkP1Pl52ZR.QDA6vI9ZpwGxSVf+k5m2cucSXzqanmiza86tQ8ZGu0t4xM7nBa8vbGNpUmN1ec+AaWs3GswNMOpQuG9vFCys2Ya2Uu2v6rQc8lkKTtDZ8cN09vb09h8o8a2nSmxGYe7weM9L68u+le9dOHeuusgd+sc+nC12hR9lS6Mp01U+bfNO792kdmSJ16vuozgiZFb1t9z520S2oS0d4fupzcyYTtemiMqcX610yk4wJJ2qEWTf.5gmAwW3AvZfOAxFSjcPZPu4eL37.lBQ2zAZjfvzYDpplNT3lTxfd1foASi81pxfzUNMVieXkyjG7Haqfgw.NqxPr8fgRoAZWIjGELzMfUFeZ06zn6Aa6gFMT4nASRE7Zp5EyuowFqqWrnhc.1cBhqpVrjwlaTbiB5RvMXTXnudQi0yuw5ETBvmFHmUIWEk5en9cqpokIxvskEO9CvCZbl.tP+DrCn8zgPQvDaQrvrnaerNeHjhnC8QOf5crOjkJNNFGfq9XuSvcn1fnQAGYVNw73tbjPHs8H3FfeLjH.kzvCMXRP+GyrYiNJt5y1i47z9Eq3JmYNLDcpri0nXgVI06nJhapEF3j5oCId6A4bCY8wlvapxu7SQb6cOdXCF7qpFkDRhSE33prQ4M2nbYcCkv.u2eN91KjjF5cGy9ZdSKoVVN3IoHDi4mtcBcvgOQVG.pqD5f2S8AnSv8gzvz1FSfirY0BoCYE84nGhx8aV8Poxk1znfw7NYWPmLC4iYvQJZve0eJmrm72l1ICTVIbxda0NdXHbbMO5i7AcrrOVQ8hE1rrQgRFSIEEM1n75aZT1XJmrHeok9wkDNSrvDcAEYswAATRT53gX15zQHtMueUeXQF6RR30vlBuvKu4SNKpo+LqIDTSL8DnhACwYA4kkUZ9Hhfzcl+Vb.l.G3yGWCnZifyAWWLxybXMn3AIDMQmP8.EFqn1HtHlIjQmfrwNNcPACmf2OgRJTVaA5QKbMpGnsRfe2wtBUKiLwMUhwOfYob.KsX.wWBv0f7uKL02ZOmvAv+E9drisePUHy2H4LbGVad+WDUBN6.5i5frr.q8EktH0cM5XhESR+RAh1TuvSnowDaUNMlI54YvN00wu4BkDw43pBeSEO7ylId3mUwGXxVDgGZXxUyVV+MTitmVtKCrdwDW4ShR6iJ5TtWMuvZ8vhxh2Tsicf4v4yiKMGdDxh4kAOF1vl2Rcq98gJihYvUTa9Eub5Ni71eEw1+GU21gdDxIVQAWSCbBVzkFU0saW+ozqs+yh1qsQKbu1lt.gUVrBDdFsJakKcsJaQsWemvSn3zh7eE5UkZII17lB17pwYHy4veu57xVMAS1lRniFRI1lxFJGfgDXFL.r0jadqn8WmqnUMH.JFODx2+j+oWk6.G8xKaCrIJQI.cG6Gjvr8mt8APTTn753TV7pv5S1razNXPdlELO0Z4Ejuoy.MbalA9yw4i9yqK8pp2GNALYpM1oy6EMTNw5moEjzw.ToPODmah0wS5o1T5c6ivNI0iOW2dp+x+F9k+08M7GPGyxWWTIEb+MjGlnozvtSfLEXcbI0RrlRHFmmMloA5hIV7A+O3KDoNabpPj5SPpzNp6YgE3G1YOH2j3hQtt5AXeJgEafUOhvnPv9L1gWEqP3jNPTU0ykWo53SCQ+FpebD.oIkGfEa.x0DRp82NwSHssGc7HtV+cE.v91PEGZb35uHdFoEOz1VDlaTy1xqXcjmmMTYmPfi17+cjc8LXtGwFTrTNqT0ExSLPloCwFVtpzFEhn6HH8XKYJXbeWLvpV7kzOQbjkeYDL9M+Eav3Wi42l3o0ROgG6Z6NxAOIna30egO5TDzKXj3mc3W36cqLcnTk+TkcfDHQdSGP8EVff48Jiy835CTErqFyyT6Wtkk7q6fVyyx92o1g5blvPsosSPX8HoUECdZWbqnD83cxM5a+vAUJT3GtcRSyOnx9iQNIztee0vDf94p4eFVxqrflGPN1SDJsKMW+bS0DuzYzK6G2NV4Rq+4dyScHKdp6zM7clF510kRCFx6Yobz3VUlNV1EOOT9dxe9YloP7CdC4l7z62cbRKoVdxCPKqL5weg.wj3OqPrkrhzidO89nnjnmxL82Seel2yYyl6heYEyk6x8Ep+A0POXMlR7xMudc08ubyfWK7oEzl1o9xB6IRq80H689S5MB6Ab3EZDV887dPmWoMTaOy.fE54gH9in9Xc4UtK10tGkf8S.cJJLlKEFIK8W7jTy.JwrXphlfpPZdWoxDfFx.6fHIVLXbhUpschFbKJrRTDyd9lfhgGMR5LuyXGeL+sGzk6CSLXCYv2A4YAmgIBT8xoTn232JE52xo905oX63Wb+x4o36qBtzFZ7iRsWOmkuJ5p1uV1CWjoG8qLE+MOwth6JbHftkv+ymNMTz.LVSe1+Robgq29JSyjK0LDZbQIrvEkvhWTBKcQIb8KJgkunDtwylPVzmpPgWtB+OHJbmsD+MLkRD.l6Jp7+Ioeo2O