I really like some of the pics. Outstanding finds given the huge number you presented.

(Though for one note i really dislike the one for Lorelei Coral (i wasn't even very fond of the modified version of Cuteunit but that was miles and away better. This one here has just not one ounce of the style of FFH2 Leaderpics or overall art unlike most others you presented and which fit strikingly well with the overall feel.

I hope Kael takes note and uses some of these if its possible to get the OK from the creator.

) and think the second presented Luichirp Leader really looks strongly Khazad. Maybe switch the first one of the Khazad (which might not be perfect but seems like a far better match) with that one?)
One important comment on balance though: charismatic is way to strong a trait in the hands of the Sidar (i can't emphasize that enough...). Even if a second one is not gained. That would be way beyond what Sandalphon can do (and Sandalphon has relatively week traits because the is rather strong otherwise...

).
I would chose that Leader if playing Sidar above any other Leader without charismatic i could hands down (if such a thing whould be possible in the first place). Just for that one reson.
And it also simply doesn't fit the civ imo. The grey are many things. But not emotional (that is what they lose over time.).
But i have to say a rare good pic for sidar style... (many pics presented as possible leaders i have seen so far don't really hit the mark.)
Raiders (much less important for Sidar than for many other civs) might actually be a better fit. Even regarding the picture and is fitting the civ somewhat.
As might Organized (which is quite powerful for the Sidar given that command posts are of exceptional use to the Sidar.).