Dark Elves : I've made Lizardmen lower because out of the "early" races, it's the only one that has decent access to power, the thing Dark Elves are mostly about. Lizardmen can have both WGs and ATs and even Cathedrals, missing only research buildings and the Parthenon. Still, none at all is overkill, +1 or 2 might be better.
High Elf is +2 for gameplay - the two races are very similar and I would expect at least similar races to work together - by far the most useful race if you go after a magic power strategy (you should be if you play Dark Elf) is High Elf due to being the only Arcanus race capable of producing power. I prefer not to penalize what I perceive the correct play (which does not result in poor balance - High Elf cities aren't giving anything new or better for a Dark Elf, it's just an extension of their existing strategy. With their growth, razing and building Dark Elf cities on Arcanus is not much of an option.). I understand the flavor reasons, which is why it's not zero but +4 is not really an option.
Also, if you get hold of an early Arcanus city without an open tower (Shadow Demons or Life magic), you'll want it to be High Elf to add the most your magic power. So it definitely shouldn't have unplayable levels of unrest.
Draconians : I don't think a dragon can find anything more humiliating than having to deal with bugs. Also dragons are highly individualistic while Klackons are highly collective. Gnolls are that way for symmetry. Dwarves are just too good for Draconians (massive amounts of gold to spam buy Doom Drakes or other superior flying units). Trolls, well, Draconians are good enough, they don't need easy access to regenerating armies on top of what they already have. Especially not trolls on a flying airship (yes, I'm aware anyone can buff a ship for the same purpose but at least that takes some experience to learn. An Airship does not.). These also result in symmetry btw.
Aside from Dwarves and Trolls I don't think any other race can add anything really important to a Draconian player - you'll want to keep using flying armies as much as possible, and have great economy of your own.
Gnoll : I think in the eye of a Troll, a Gnoll is a fragile verison of themselves - same offensive power but no regeneration or hit points. I don't think they'd like to be rules by someone they perceive as "weaker". Generally I don't want zero for Troll without a reason.
Halflings : I guess adding some unrest to the more savage, militarist races makes sense, but only those.
High Men : Don't understand, if Trolls are man eating monsters, why reduce from +4 to +2? I don't think I would want to be ruled by food. Aside from these, only 3 races have more than +2 : Draconians, Orcs and Lizardmen at +3.
Lizardmen : Is 0 with Halflings, you misread the table?
Revised version :
High Elf is +2 for gameplay - the two races are very similar and I would expect at least similar races to work together - by far the most useful race if you go after a magic power strategy (you should be if you play Dark Elf) is High Elf due to being the only Arcanus race capable of producing power. I prefer not to penalize what I perceive the correct play (which does not result in poor balance - High Elf cities aren't giving anything new or better for a Dark Elf, it's just an extension of their existing strategy. With their growth, razing and building Dark Elf cities on Arcanus is not much of an option.). I understand the flavor reasons, which is why it's not zero but +4 is not really an option.
Also, if you get hold of an early Arcanus city without an open tower (Shadow Demons or Life magic), you'll want it to be High Elf to add the most your magic power. So it definitely shouldn't have unplayable levels of unrest.
Draconians : I don't think a dragon can find anything more humiliating than having to deal with bugs. Also dragons are highly individualistic while Klackons are highly collective. Gnolls are that way for symmetry. Dwarves are just too good for Draconians (massive amounts of gold to spam buy Doom Drakes or other superior flying units). Trolls, well, Draconians are good enough, they don't need easy access to regenerating armies on top of what they already have. Especially not trolls on a flying airship (yes, I'm aware anyone can buff a ship for the same purpose but at least that takes some experience to learn. An Airship does not.). These also result in symmetry btw.
Aside from Dwarves and Trolls I don't think any other race can add anything really important to a Draconian player - you'll want to keep using flying armies as much as possible, and have great economy of your own.
Gnoll : I think in the eye of a Troll, a Gnoll is a fragile verison of themselves - same offensive power but no regeneration or hit points. I don't think they'd like to be rules by someone they perceive as "weaker". Generally I don't want zero for Troll without a reason.
Halflings : I guess adding some unrest to the more savage, militarist races makes sense, but only those.
High Men : Don't understand, if Trolls are man eating monsters, why reduce from +4 to +2? I don't think I would want to be ruled by food. Aside from these, only 3 races have more than +2 : Draconians, Orcs and Lizardmen at +3.
Lizardmen : Is 0 with Halflings, you misread the table?
Revised version :
