Did you note your food allergies on your reservation? I believe you can check boxes for those...although I believe shellfish &/or fish (I forget) are the only meats that you can put that you are allergic to. The rest, you'll have to explain when you get there.
We've eaten at CRT twice, and I'm a vegetarian. I specifically remember that when I ate there, nothing other than the designated vegetarian items on the menu were offered to me. I don't know if there is anything currently on the menu that's a designated vegan dish.
Typically if you've noted on your reservation that someone in your party has food allergies (my D does), your server will send the chef out to discuss your options with you. I followed a vegan diet for 3 years, and in the old days you could note that on your reservation (I don't see a way to do that anymore). When my reservation was noted as vegan, the chef would come out and talk to me...some would ask me what kinds of food I liked and would offer to make special (off-menu) dishes for me, and some would just point out what items that were already on the menu/buffet would be ok for vegans. In my experience, it was completely luck-of-the-draw and would depend entirely on the chef you happened to get that day. As my screen name implies, I am very shy and have never actually asked for anything special to be made for me (in fact, I hated the fuss of the chef coming over...I don't like to draw attention to myself and found it embarrassing, which I know doesn't really make sense, but oh well!).
It's my general observation (we've been going to WDW 1-2x per year for the past 20 years) that the heyday for chefs making guests special dishes has passed, the high point for us being in about 2005-2006. It seems lately that there is more of a movement at WDW for already having items on the menu that fulfill common allergy requirements, and indeed, many restaurants even have a separate "allergy menu" where it says basically, "if you're allergic to X and Y, you can eat Z dish." The one notable exception to this that I know of is Chef TJ (who's still going strong with his love of cooking special things for vegans and allergy sufferers) and a chef at Mama Melrose last year whose name I unfortunately didn't get. Other people may have experienced different things (and maybe that's because of my reluctance to be a "squeaky wheel" and ask for something different if I don't see anything I like on the menu), but this has definitely been my experience over the last decade or so...less offering of "specially made" items and more "here's what we offer for that allergy."
If I were in your shoes, given how expensive the CRT meal is, I would call Disney Dining and ask them to connect you directly to the restaurant/kitchen (I have done this in the past...I was nervous my first year at WDW following a vegan diet and called every restaurant to make sure they had something I could eat there). Again, YMMV...some restaurants I called acted like I was rude/crazy to be calling, and others were very kind and reassuring. If you know that you specifically only want to eat veggie sausage and hard boiled eggs that day (I'm not sure if that's what you're saying or if those were just examples of things you can safely eat), if I were you I would definitely call and ask them if that can be accommodated...or if they can make something else that you can eat. That ressie is so expensive that I would be very sad for you if you paid that price and then were just given a piece of bread and a bowl of fruit.
I hope this has been helpful in some small way! I wrote it in the spirit of understanding what it's like to struggle with food allergies (my D) and trying to find food as a vegetarian/vegan.
