I I used a unmoded IBFG . The changes are only 2
1) chavalry unit are not so strong.
2) victory condition are changed - ERE and WRE dont need other empire's province to win.
However I got same CTD at the end of Roman turn before I tried these changes.
It seems same problem of Chipirone it seems appear in a random roman turn usually in the first 10-20. The 5.03 dont cancel CTD in the savegames where the CTD appeared. Something that Roman does causes the CTD.