Can you please post the specific entry (to the CIV5Worls) here? Then I will have a look!
I have changed CIV5Worlds.xml located in 3 locations listed under as I do now know what files the game use. But I recon it is the one in expansion2 folder.
Steam\SteamApps\common\Sid Meier's Civilization V\Assets\Gameplay\XML\GameInfo\CIV5Worlds.xml
Steam\SteamApps\common\Sid Meier's Civilization V\Assets\DLC\Expansion\Gameplay\XML\GameInfo\CIV5Worlds.xml
Steam\SteamApps\common\Sid Meier's Civilization V\Assets\DLC\Expansion2\Gameplay\XML\GameInfo\CIV5Worlds.xml
Example of entry: (change I am trying to make)
<Row>
<Type>WORLDSIZE_SMALL</Type>
<Description>TXT_KEY_WORLD_SMALL</Description>
<Help>TXT_KEY_WORLD_SMALL_HELP</Help>
<DefaultPlayers>
10</DefaultPlayers>
//I have changed/raised this number on all map sizes by 2 in this file to make games a bit more crowded. But number is not changed when I try to host a MP game!
<DefaultMinorCivs>12</DefaultMinorCivs>
<GridWidth>66</GridWidth>
<GridHeight>42</GridHeight>
<FogTilesPerBarbarianCamp>23</FogTilesPerBarbarianCamp>
<NumNaturalWonders>3</NumNaturalWonders>
<UnitNameModifier>30</UnitNameModifier>
<TargetNumCities>5</TargetNumCities>
<NumFreeBuildingResources>3</NumFreeBuildingResources>
<BuildingClassPrereqModifier>25</BuildingClassPrereqModifier>
<MaxConscriptModifier>0</MaxConscriptModifier>
<TerrainGrainChange>0</TerrainGrainChange>
<FeatureGrainChange>0</FeatureGrainChange>
<ResearchPercent>100</ResearchPercent>
<NumCitiesUnhappinessPercent>100</NumCitiesUnhappinessPercent>
<NumCitiesPolicyCostMod>15</NumCitiesPolicyCostMod>
<AdvancedStartPointsMod>90</AdvancedStartPointsMod>
<IconAtlas>WORLDSIZE_ATLAS</IconAtlas>
<PortraitIndex>2</PortraitIndex>
</Row>