Okay, I won't say the Veganomicon. :-) I like all of Isa's cookbooks, but I can understand wanting something very simple when you are busy with kids. I think Joanne Stepaniak might be a good author for you to look into. I have her Ultimate Uncheese Cookbook, and though some of the recipes are a little time-consuming (especially if you count things like soaking time), others are quite simple, and most of the dishes are mild-tasting. I like the recipes a lot, even though I also like spice. I read part a book she co-wrote, called Raising Vegetarian Children, and it seemed good. It is not all or even mostly recipes, but I imagine those that she includes are worth trying.
How It All Vegan, by Tanya Barnard and Sarah Kramer, includes a chapter of recipes for children. I like the book as a whole, though I haven't tried the kids' recipes. I would say that most of the recipes are slightly easier than the Veganomicon's.
Another favorite of mine is Everyday Vegan by Jeani-Rose Atchison, but I would say that its difficulty level is about the same as the Veganomicon. It is healthier, though.
Because I am still pregnant with my first, my experience of cooking for children is limited to my nanny career. I have worked for a family that was mostly vegetarian, and I did prepare some vegan meals for their children, but of course, I was limited to the ingredients I found in their kitchen. Those children seemed to like very simple food (too simple to even have a recipe) best. For example, I tried making them chickpeas in some ways that I enjoy them, but it turned out that they liked them best just poured out of the can and rinsed. They loved steamed vegetables, but only wanted them with a little butter or oil. They got angry when their Dad walked in and put cheese on their broccoli without their consent, and one of them outright refused to eat it. Any kind of sauce would have been wasted on them. In my experience, the best way to get them to eat multi-ingredient dishes instead of piles of single foods was to have it in patty or nugget form, such as a veggie burger or frozen "veggie bites," which contained cheese, though I plan to try making something similar, but vegan, from scratch for my own child.