As per page 89 of the official forum thread (http://www.minecraftforum.net/forums/mapping-and-modding/minecraft-mods/wip-mods/1445251-1-7-10-beta-wip-colored-light-progress-and?comment=1775), the current version of the ColouredLightCore does not agree with forge's loading screen.
http://pastebin.com/EmLnaQQC
Something to do with the font renderer perchance?
You probably already know about this, but better to make sure.

TY for the report... It's known, but there wasn't an issue tracking it here.