Hey, not a bad list you've got there. I have a few changes though.
1) I'd go with The Lore of Shadow on your Sorceress, it just works excellently with Dark Elves. I understand Lore choices may be down to personal preference, so if you want to stay with Dark Magic, I'll let it slide
2) 20 Warriors aren't going to cut it, I'm afraid. 32 is usually the lowest I'd go. I personally don't think 12 Black Guard are enough either, so you could drop them and add more Warriors. Or, depending on Percentages, vice versa. Alternatively, you could swap them out for more Crossbowmen and/or Black Guard
3) I personally would split the Crossbowmen up into two units of 10. They work great in a
MSU Style, I find. It gives you the flexibility of being able to split fire or concentrate it on the same thing if you want; if an enemy
CC Unit closes with your unit of 20, all of them will die (or, at least, not be able to shoot next round) so splitting them up ensures they'll last longer; finally, you don't have to deploy them 10 wide to get all the shots in.
True, you might be using them as sacrifices for your Sorceress, but I find Xbowmen too valuable to just kill. Your choce though
4) Like I said before, the Black Guard are a little... lacking in numbers, so bearing in mind the advice in 2) may come in handy.
Hope this helps!