I thought of another way to reconcile the discrepancies between BOT and ENT's Romulan War. Use the Vulcan's ties to Romulans as a justification for alleged secrecy about the events of Earth-Romulan war. T'pol knew the name Romulan in the episode "Minefield". She stated "They're rumored to be an aggressive territorial species; but the Vulcan High Command has never made direct contact with them". Well we know that's a lie from the episode "Kir'Shara". I'm willing to wager the Vulcan High Command was very much aware of who the Romulans were and were in contact with them prior to the events of ENT. Normal Vulcans like T'pol and the rest of the general population were probably in the dark about the Vulcan-Romulan connection.
I could see the Vulcan's covering up or hiding the nature of their relationship (political and genetic) they have have with the Romulans; from Earth and other Coalition planets.
If the Earth Romulan War was supposed to take place in Season 5. This would be on the heels of the Terra Prime incident, xenophobia and Xindi conflict. The populace of Earth would still be mistrusting of any union with alien species. Add in to the mix an interstellar war with the Romulan's; who are genetic cousins and outwardly similar to Vulcans (ignoring those stupid brow ridges). I doubt Starfleet or the Earth Government would be able to sell the United Coalition of Planets idea to the population of Earth. Suspicion and mistrust of aliens, especially Vulcans would increase.
I could see either the Earth Government, Starfleet and the Vulcan government (Post Kir'Shara) deciding to hide what the Romulans look like and any contact that may have been made between Earth vessels and Romulan vessels during the war. The truth would be revealed in a later date presumably when the people of Earth were more enlightened and had experienced the benefits of the United Coalition/Federation. Until an incident like TOS "BOT" or ST09 exposes the Romulans to Starfleet and civilian persons and the government has to explain and pursue information about the Romulan threat to it's populace. This could reconcile why Spock was not completely certain the Romulans were related to Vulcans in BOT. However he's aware of the relation in "The Enterprise Incident", "Unification" and ST09 (post Kelvin destruction). Also why Uhura is fluent in all 3 dialects of the Romulan language in ST09.
Staying true to canon of BOT, but bending the rules so you can have a plausible presentation of the events of the Earth-Romulan War and the aftermath.