So I've been messing around with some custom biomes, and mostly trying out different custom trees of my own making. This time I was going for a 'mirkwood forest' type biome, and so was aiming for a very thick layer of leaves, so much so that the forest floor is almost entirely unlit. I had great success with this, but upon wandering farther from initial spawn I found it to suddenly get much lighter for no apparant reason. Entire sections of the forest will be mid-way lit while identical sections are practically black, and neither having any open blocks for sunlight to get through. I'll attach a picture of a few particular offending light spots. I initially was running the latest supported terrain control version and bukkit version, and then switched to dev snapshots of both, so now running 1.7.2 and it still persists. I also tried removing all my other plugins and re-generating the world but to no avail.
Any help would be appreciated! This is all (right now) that stands between me and an amazing middle-earth themed biome. I'll likely upload it to the forums once I can get it finished.

The diamond blocks show two particular spots of light which have no cause, there are no openings anywhere above them. Placing torches there and breaking blocks makes no difference, even opening and closing holes in the canopy don't make it go away.

Frustrating, but light isn't handled by Terrain Control. Maybe Terrain Control isn't placing blocks correctly, but if it is placing the blocks correctly there isn't much we can do.

That makes me very sad. Well regardless, thanks for the help! Also, I really do love this plugin, and the changes you guys have made to improve it from what it was, it's nothing short of spectacular.

I usually recalculate the shadows after the map is generated, I think
NoLagg worked quite last time I tried.

Really? Definitely going to get my hands on that, thanks for the tip. Now as far as I know WorldBorder is a good tool for generating large areas of land, but as far as I know it automatically creates borders, which I don't want. Is there a workaround for this or an alternate plugin? Note: if you don't have this info already or know anything about this in particular don't worry about it, I can do some digging. But if you've gone through this process already then it saves me work :) Thanks!

You can just pregenerate using WorldBorder and disable the plugin
afterwards. If players go outside the pregenerated area, terrain is
generated as usual. I'd pregenerate the map anyway, because terrain
generation can lag the server, especially if you are using TC and
complicated settings. Hope NoLaggs lighting fix still works, good luck!

Ahh, I was wondering if that might work. Yeah, I noticed it having lag spikes intermittently, especially it seemed with maps with a lot of custom bo2's. Well thank you so much for the help!