Okay, I've been checking this stuff out as best as I can during the interim.
Now that I'm back I'll tell you what I've turned up so far.

I checked out both the "EB/mp game edu backup/" (3 files: Rome.lnt, export_descr_unit.txt, map.rwm)
&
"EB/sp game edu backup/" (appears to have the same 3 files: Rome.lnt, export_descr_unit.txt, map.rwm)

Don't know if the content of these files are complete, or if they are located where they are supposed to be, and if not, where I should move them to. But I'm thinking that you may have been thinking that one of these folders may have been missing (or missing one or more of these files)? and that may have been the cause of the no-show Imperial Campaign in the single player menu que?

Still checking the other folders to see if something shouts out at me that might be useful for either me or anybody who may attempt to help me solve this problem.

Nothing useful in the "EB/Data/Menu" folder.

I found a "MENU_ENGLISH" file located in the "EB/Data/ Text/" folder. It seems to describe how things are supposed to happen. I see where the Single player and EB Imperial campaign lines are located, so if the game was reading this file aand it is where it should be then that is not the problem.
Still nothing that may correlate with a "sp game edu backup" folder or file, no luck yet.

The "EB/Data/Maps/Campaign/Imperial_Campaign" folders and files are there. Don't know if a key file is missing that would let the imperial campaign to show in the menu, though.

Okay, I've checked through all of the folders and files in the "EB/Data" section, now on to Documentation....

Nothing obvious under the "Lighting," "Modesty," "preferences," "presets," or "saves" folders.

4 files under "EB/Validation/" (eb.jar, edtftpj.jar, jzlib-1.0.7.jar, & ebIgnoreList.txt) Not sure if the txt file is accurate but I do see a line that has "campaign" in it.

I clicked on the EB/validateInstall.bat file to see what it might tell me. I already downloaded "Java" earlier because it recommended that I do.
I'm running XP with SP3 but I offered a specific checklist to download for the validation comparison "test" so I don't know if any of the following is relavant to anything.

The Validation check listed the following: an "Exception" in the "main" java.lang.NoClassDefFoundError: europabarbarorum/ValidateInstall
Caused by:
Java.lang.ClassNotFoundException: europabarbarorum/ValidateInstall
at:
Java.net.URLClassLoader$1.run (Unknown Source)
Java.security.AccessController.doPrivileged(Native Method)
Java,net.URLClassLoader.findClass(Unknown Source)
Java.lang.ClassLoader.loadClass(Unknown Source)
sun.misc.Launch$AppClassLoader.loadClass(Unknown Source)
Java.lang.ClassLoader.loadClass(Unknown Source)
Java.lang.ClassLoader.loadClass(Unknown Source)
Java.lang.ClassLoader.loadClassInternal(Unknown Source)

Could not find the main class: europabarbarorum/ValidateInstall.

The ebValidation Results.txt was blank.

I don't know what that string of gobbligook meant, and if it was revelant to the "Imperial Campaign" screen not showing in the menu, or not?

Anyway, I've now looked at every EB folder and file (obviously I haven't read each txt file completely, line by line, but if the title sounded like it might be relevant I gave it a quick, once over.
Still, since I don't really know what I'm looking for, or what to do with it even if I find it, I'm not sure how helpful this exploratory exercise was/or is, unless somebody out there in la-la land can provide me with better insight?

I'm hoping somebody will see this thread and say, ah-yeah! I know what needs to be done and offer me a quick fix here, but I'm afraid I may just be farting in the wind, and the wind is blowing against me....