It is very simple to port mods like Roma Surrectum II into Rome II, just:
- Add a Battle Map Editor
- Add a Campaign Map Editor
- Enable UI Coding (not only reskins)
- Unlock the UI Limitations for Buildings and Traits
- Unlock the UI Limitations for Descriptions and Texts
- Unlock or De-Hardcode the Database
- Add a Population System
- Add a Family Tree
- Add Roads
- Enable Intro / Cutscene Modding
- Enable Sound Effects and Voice Modding
- Remove Torching Down Gates and Improve the Siege AI
- Add Diplomacy Option: Trade Region
- Release a Scripting Doc
- Add the Senate
- Fix Night Lighting
- Add Dynamic Weather to the Battle Maps
- Add Dynamic Day & Night Cycle to the Battle Maps
- Improve the Battle AI
It's not about carbon-copy porting RS or EB or RTR or whatever, though. What's the point of doing that? They already exist, why would you want an EXACT copy?
Rome 2 has some advantages over Rome 1. Rome 1 has some advantages over Rome 2. Simple as that - hell, most of these aren't even "advantages", they are "differences".
And some of the things you've listed I haven't seen in the original Rome or it's mods: when did Rome 1 have dynamic weather or day/night cycle? If I remember correctly, Rome 1 had separate night battles, just like Rome 2! And honestly, I can't remember seeing much weather in Rome 1... but I've not played it for a while.