Solution : https://service.sap.com/sap/support/notes/875157 (SAP Service marketplace login required)
Key words :
620 sapkb62055 640 sapkb64015 700 sapkb70005, central system log, version #02for release 6, central syslog, heterogeneous networks, main instance, illegible characters, individual characters, displayed differently, version #05 rslgsend