Head Serf only has 17 in the included scenario as is. I don't think the number of civs available to the scenario is the problem, but the fact that the mod included map is not large enough for so many civs. I'm not saying we need a bigger map, either... I think it should be up to scenario makers to use the mod provided materials in a creative manner to make the scenarios they wish. I'll likely add some of these civs to my Age of Kings scenario if we go to a 24 or 32 civ mod... I'm stuck at 18 right now.
I think that if we go to BTS someone can definitely create a scenario with the above mentioned civilizations, but it does not necessarily have to be the one included with the mod. For one, the map would likely need to be increased in size.
As well, we would not need to add any new civs to the mod to do this... some civs could use the same Civ UUs and Leaders. Sweden and Denmark could both use the UU and Civ characteristics of the Viking Kingdoms Civ (an additional Viking leaderhead added to the mod would help vary that aspect).Kiev, Moscovy and Novgorod could share the Rus UUs in a similar way. Others could be done similarly as well.
I think adding a second leaderhead to each civ would be helpful, actually. Because the current traits were selected, in part, to make certain every combination was available in at least one leader, some odd choices came about... a Seafarer Otto, for instance. A second leaderhead for each civ would allow a more historical redistribution of leader traits to civilizations, and allow a better choice of leaders in scenarios. For instance, in my scenario I wanted Olaf of Norway to be Pious Seafarer... unfortunately, the only one with that trait was Theodora, so I had to select a different leader to lead my Norwegians. I think it ended up being the Italian leaderhead... Financial Seafarer.
As I've repeatedly said, don't get the mod and the scenario mixed up. The mod has over 30 civs that can simulate almost any civilization in the middle ages... someone mentioned the Kingdom of Sicily/Naples. Weren't those just the Normans? Well, if so, I would use that Civ and rename the leader Robert (or Roger... don't remember) and the civ, the Kingdom of Sicily and Naples, in the WBS, and use it as is. It doesn't even matter if the are two Norman Civs in the scenario... simply pick a different Leaderhead if you wish, or live with using the same one.
Anyhow, this all started when I mentioned I wanted more civ slots if we went to BTS. I don't need more civs, just the slots... I'd like another Viking in my BTS mod, and to add a couple of Irish Civs and perhaps the Picts and Visigoths. Note, none of this will require new civs be added to the basic mod... I'll use the Scots for the Picts. And have multiple occurances of their father Civs for the various Viking and Irish kingdoms.
Finally, since this all hinges on the mod being adapted for BTS, it should be noted that BTS has the ability to combine mods... some sort of modularity. I'm uncertain how it works, but if there is the ability to combine mods, then people could, on their own initiative, make modules that would combine with the EMA mod to tailor it to their specific needs. For instance, when I get BTS and we move to it, I intend to develop a mod component for my Viking age scenario... largely to make the Wonders and Religions conform to the geographical location of the mod (that being NW Europe). Others could do likewise, if for instance, there is a civ they figure ought to have been included in EMA but wasn't. A mini-module to go with EMA containing the altered files and added graphics for a particular civ ought not to be too difficult with BTS's modularity.
There... a bit long-winded, but so it goes.
but still!
no worries man! 
