As it stands, factions are mostly cookie cutter. They all have the same terrains, either evil bad dead land or goodly good grass land, and they all have some pretty unbefitting attitudes. So here are my suggestions.

Altart

Same Terrain

Same Color Scheme

Gains Trait: Egalitarian (fits their description)

Attitude Type: Aggressive Expansionist, tries to grab resources that are near it's borders.

Bonus Modifiers: Lowered Perceived Value of Others diplomatic requests (Dislikes being told what to do), Increased production of Materials and Metal

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Capitar

Same Color Scheme

Terrain Type (undecided)

Attitude Type: Economic and Military, emphasis on research and buildings that increase guilder production, fields standing army with wealth, techs up military with basic equipment

Bonus Modifiers: Cheaper recruitment cost, Lower equipment cost

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Gilden

Same Color Scheme

Terrain Type Changed to Desert (They border desert, fits well with general theme)

Attitude Type: Heavy Emphasis on production, increasing guilder production, heavy emphasis on acquiring mines and quarries, emphasizes trade, tries to get trade treaties.

Bonus Modifiers: Gains an extra trade rout for all towns, gets more from trade

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Parith

Same Color Scheme

Terrain Type Changed to Winter (They're in the north, and it fits well with their general theme and profile)

Attitude Type: Heavy Emphasis on Diplomacy and Arcane Research, tries to make treaties with other kingdoms

Bonus Modifiers: Higher perceived values on all offers, Improved disposition with other Kingdoms (but not Empires), Other Kingdoms are hesitant to declare war (but not Empires)

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Tarth

Same Color Scheme

Terrain Type Changed to Grassland Swamp

Attitude Type: Generally mixed personality type with an emphasis on exploration, fields archers.

Bonus Modifiers: Gains movement and combat bonuses in Swamps and Forests

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Kraxis

Same Color Scheme

Terrain Type Changed to Desert (It fits their location, background, selection display background, color scheme, and general theme)

Attitude Type: Treacherous Traders, likes to increase Guilder production through the use of trade and markets, hoards wealth, likes to bribe enemies to go to war with each other.

Bonus Modifiers: higher perceived value on all offers given and lower perceived values on all offers received (dishonest traders)

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Magnar

Color Changed to Dark Red (Dried Blood)

Same Terrain

Attitude Type: Empire Oriented, focuses heavily on expanding and consolidating borders, increasing influence, and fielding an army

Bonus Modifiers: Increased recruitment speed.

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Resoln

Same Color Scheme

Terrain Type Changed to Winter (They're in the north, it fits their general theme, and is fitting for their crest)

Attitude Type: Heavy Emphasis on Arcane Research and War, tries to get Wargs early, likes to field mounted units with leather armor, Territorial Isolationist attitude type, doesn't like to go to war with distant kingdoms/empires

Bonus Modifiers: Diplomatic penalties with empires too close to their borders, lower perceived value on all treaties, Wargs produce faster

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Umber

Color Changed to Brown (Matches logo and fitting for the empire)

Terrain Type Changed to Desert (The land was wasted)

Attitude Type: Heavy Emphasis on warrior production, military and warrior culture, secondary emphasis on trade

Honorable Military Culture, Seeks to maintain peace with mutual allies, Merciless in war, Seeks war with enemies of friends

Bonus Modifiers: Diplomatic Penalties for Dishonorable acts (betraying treaties and such), Diplomatic bonus for friends of allies and trading partners, extremely low perceived value of peace offers, increased perceived value on trade agreements

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Yithril

Same Color Scheme

Terrain Type changed to Barren Swamp

Attitude Type: Bandit like behavior, focuses on military and adventuring, builds and equips armies and frequently attacks monsters the armies can dominate, quick to go to war with enemies they could easily dominate, sends injured units to nearby swamps to heal (hit and run behavior)

Bonus Modifiers: Improved movement and combat in swamps, minor health regenerates in swamps