The minor errors are always getting fixed. I wouldn't entirely classify it as a matter of priority. It's just that so many things are getting added and changed constantly that these kinds of minor errors crop up all the time.
Also, English isn't Darkgod's first language, so some of the typographical errors can be cropped up to that. But that's fine, he has a loyal community to beat him over the head with corrections
How does Tome development work? How do you go about submitting patches? Does DarkGod approve/reject them personally, or is there a team of developers with commit access? If the latter, how much leeway does each developer have for things like revamping UI or tweaking game balance?
It depends on whether you want to submit stuff for the actual game or if you want to go and develop stuff on your own. Go check out the Addons page on te4.org and you can get an idea of how to submit new content that can be added into the game. If you're looking to develop for the main game, PM DarkGod. I'm pretty sure that he's the only one doing the development, but I'm probably wrong.
Post ideas/patches/discusions on the forums; I read it all
[tome] joylove: You can't just release an expansion like one would release a Kraken XD
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[tome] phantomfrettchen: your ability not to tease anyone is simply stunning