Am I the only one to think the sovereigns are all too similar, in particular stat-wise?

All of the kingdom sovereigns have exactly the same magics.

All of the empire sovereings have the same magics.

The stat variability is between 5 and 15. There's no 5. Strength, charisma, constitution are at 15 for nobody.

Here's a quick checkup:

Relias :       12 11 11 12 10 12

So he is good at nothing in particular. Adventurer + Hardy, he should be good at adventuring: Strategic movement and lots of hit points.

Why average stats? Do they help him in any way as he'll be adventuring. If he's considered a jack-of-all-trades, it is reasonable, but I don't know why anyone would pick him.

Procipinee:  10 15 10 10 15 10

Great. She's a good wizard. Good sovereign.

Carrodus:    13 10 10 12 10 10

I'm not sure if 10 constitution and hardy make sense. I think not. Either hardy is more interesting than 3 constitution points, in which case all the sovereigns should have 3 less constitution and hardy, or Carrodus should have 13 constitution and not hardy. Hardy provides 10% hit points increase if I understand well. So unless you expect to ever reach 40 constitution, hardy is not interesting (at 30 you get +3 hp, which you'd have had from the start with +3 con). So, right now I'd ditch hardy out of the way or make it provide 20% bonus at least or reduce the cost to  4 or 5 and not 10. I don't think having tons of Constitution is meaningful. You'd need 10 levels of points put in Constitution to make Hardy interesting, that's not really something I'd put points in.

Replace Carrodus stat to 13 Constitution, and/or fix Hardy. Since he's supposed to be a great general and leader, he shouldbe  stronger, dextrous, charismatic, but not intelligent or wise. So here is a suggested stats: Str 14, In 8, Cha 11, Dex 13, Wis 8, Con 15. It's more in line with the background and gets rid of the worthless hardy. Alternately, make him wiser and more intelligent, but remove some spell books.

Irane:         12 12 12 15 12 14

Markinn:      12 12 12 15 12 14

Yes, they have the same stats. Irane is better looter and fighter. Markinn is a miner. Plus organised and ugly. There's little difference between them, the stats. I don't really see why a miner would be more dextrous than strong. I'd have Markinn have str 15 and dex 12 instead. Probably dex 10 and cha 14 as it makes sense for a mechant leader to be more charismatic.

Ceresa:       11 12 12 13 11 12

Description: Ceresa, wisest among the Fallen. So wisdom 11. Errr? She has to have Wis 15 or change the description.

Suggestion: Increase Wis to 15, lower str, dex, con and cha by 1 point.

Karavox:     13 12 12 12 14 13

Bland background and stats. I'd suggest removing spellbooks from the other sovereigns so he stands out as a better magician.

Magnar III:  11 13 13 12 12 13

Nothing standing out. Gives many penalties and is good at nothing. Give him less than 12 in Cha as he's ugly that would go well with, and use the points to make him useful somewhere, 15 in constitution for instance, as he's likely to spend all his life outdoors, being inefficient in a city.

Verga:         14 13 10 12 12 13

Same as Magnar. He's the strongest of them all with a mere 14 str? He has to have 15 or else he looks silly. Naturalist I don't think very interesting but that may be just me.

Kul-Al-Ulann:11 13 13 12 13 13

A warrior trait means he needs good strength, and maybe dexterity, to make use of it, therefore it's his weakest stat???? Lower his wisdom.

I suggest changing Hardy to make it worthwhile. Right now it's useless until you expect to have more than 30 Constitution, which is a long way to go (particulary since you forfeited 3 Con points from the start to get hardy).

Relias: No stat stands out, there's no little to pick him based on stats, but adventurer is great. Make the others stand out in contrast to him is all I can think of.

Procipinee is great.

Carrodus: Str 14, In 8, Cha 11, Dex 13, Wis 8, Con 15. Remove hardy.

Irane: Keep her this way, but change Markinn.

Markinn: Make him stand out. Something like Dex 12, Str 15. Cha 15, Wis 9.

Ceresa: Str 5, In 13, Cha 15, Dex 12, Wis 15, Con 12. She must be wise, she could compensate by being weak somewhere else so she is neither bland nor a Procipinee clone.

Karavox: He's bland. What about giving him more spellbooks than the others? But then other sovereigns should have less books since everyone has everything. Give him Enchantment and Summoning spellbooks and lower his stats.

Magnar: Make him Con 15 and Cha 11? Probably not enough to make him worthwhile. with more background info, stats could be tweaked to make him good at something, but we don't have enough to make him interesting.

Verga: Strength 15. Dex 15. Con 15. Reduce Cha to 9. Remove some spellbooks, like air or water for instance.

Kul al Kulann: Str 13, Dex 13. Int 11, Wis 11 at least.

Also, more diversity in magic picks. The game is called Elemental, it would be nice to see some leaders have an affinity for a given Element.