nice, I'll definitely try it out once I get the game. I'm a big fan of the anime and the novel.
Glad to see another Seikai fan. The series has such depth that I've been trying to mod it into various games for a while now, but Sins is the first one that I think has a real shot at that "you are running an empire" feel. There's a Homeworld 2 mod stalled at AbhNation, and I hope to borrow some of their models once the Sins mod tools are available.
Curious though, to how much extend the mod capture the space-opera battle atmosphere of the Sekai universe? Since most battles begin or end with a heavy mine attack and assault ship to assault ship duels. The mine attack especially can hardly work very well without an intensive intercept system. So how much adaption you had managed to incoorporate.
I hope to capture everything! Seikai is probably going to be easier than, say, a Star Wars or Star Trek mod, at least gameplay-wise, because it's fundamentally simpler: no real carriers or fighters, no ships with "special abilities" like Star Wars' Interdictors.
As for mines and intercepting them, I have a working system in place. Basically, I have made the mobile space mines into small frigates. Mine-armed ships don't fire mines like weapons, they launch these frigates, using the same mechanism where the Sova carrier lauches its missile launcher turret in stock.
These frigates have no weapons, and one ability called "detonate." This ability can only be used at short range, and does damage to both the frigate (mine) and the target. So visually, the cruiser or line ship launches the mine, which then flies over to the enemy and explodes, dealing damage.
Since the mine is a frigate, not a projectile, it can be targeted and destroyed, and it has very few hitpoints. Escorts (c.f. the battle of Aptic gate) are best at this, since they are one of the only ship classes with large numbers of rapid-fire weapons. Cruisers and the like have defensive turrets, but these have much less range than the high-power ones on the escorts.
Line ships carry 76 mines each, and can fire one per second. In my gameplay, two of them can jump into a gravwell and unload their entire load in under 2 minutes. This is enough to destroy everything in the planetary system, if those mines aren't shot down. A cruiser can take 3-5 mine hits, depending on researched upgrades and experience level. An assault ship? One mine equals one fireball.

Cruiser main guns will annihilate an assault ship on a direct hit. Of course, if you're near the edge of the gravwell, you can try to jump away. (Thinking of the Barsroil's mad dash to separate bubbles with incoming electromagnetic shells just behind....)