Well, due to buggy game of CA my mod is cursed with random CTD (in fact Runtime Error) which is caused because game has hidden units' limit per faction which is - i believe - 99 units per faction and even Swisshalbeldier's fix doesn't help. This doesn't mean you always meet that crash, but it is common and there are ways to bypass it.
Actually no real cure is possible, but removing mod ;p, still you can successfully continue playing with using some additional steps:
1. When does the bug occur?
Normally you need about 410-420 AD to start facing Runtime Error as WRE or ERE builds III-IV grade military structures which means they have almost full access to +300 units per faction. Issue regards only faction controlled by AI, it will never occur for faction controlled by player (i mean either ERE or WRE) or if you play multi with both player controlled ERE + WRE.
2. What to do to bypass it?
Thera are at least 2 possibilities. One step is needed to localize which faction creates CTD. Either observe carefully when crash happens during turn's end or use option "show all moves during turn's end" to make it possible to see, if shorter version is too fast to notice. In most cases you want to turn that option on still because of other tips noted below.
a/ (recommended) Assuming you started with FotE+EP Revised and both Auxilia (for WRE and ERE) submods on, deactivate submod for that faction you don't control (ERE, WRE or both if you don't play Romans). Now save should be free of error. If problem still exists just load save few turns back - that should work.
b/ If you really want to use both submods for ERE/WRE constantly you can use MAGA to resolve CTD/runtime error if you play settled faction and have at least 2 regions. Using fully shown moves (in options) localize region where crash happens. It is either fleet trying to move from port or army trying to move along selected region. Make solid save to be turning point if things won't work. Use MAGA to swap regions temporarily and end turn. If you managed proper region to swap game will finish turn successfully. Now you can swap back regions, no more CTD should occur. Deactivating auxilia submods here is optional, i didn't need it to bypass my crash, but for security - you may want to do it and switch it back on after successful fix.
It seems crash is one-time event when bypassed once it should not go back later, if so - try steps above again.
There is also another CTD regarding rebels - it is not mod's specific, but vanilla game bug - the only solution is to kill rebels fast enough to not let them block in the terrain. You can also use MAGA to take control over rebelling region to prevent them showing up.
Remember to use MAGA wisely, just to prevent this mod to ruin your campaign because MAGA can be used as cheat tool, while it was not planned to be.