So even cooked they were awful? Okay, that's a bit different than fresh. Sounds like they didn't develop any sugar levels, or have a very high Brix. Not enough hot, bright sun can do that, and yeah, I'd say you're right that late maturing affects flavor too, for the worse. That's a tricky thing with paste types, many of them are later maturing by nature. I have a lot of them in my tomato collection and many are just right on the line when it comes to maturing. I don't know much about gardening in your area, but you might be better off with a tomato type you can bottle but isn't a romano/paste type. As
@Zeedman suggested, oxhearts are a great option to consider. I don't find them as productive but they can be earlier and they are often nice and meaty, better flavor. You could also try next year some organic molasses water with your plants, seems a popular choice for many tomato growers, and it might make up for some of the lower brix due to environmental conditions.
When my kids were younger I did everything garden related as quickly as possible. I froze all my tomatoes whole, and they are really good that way. I would run them under water, the skins fall off, then throw a bunch on a glass baking dish with peppers, onions, celery, few herbs, olive oil, put them in the oven a couple hours and done. It saved me blanching, burnt fingers and sterilizing and the taste was honestly better than my stepmum's bottled tomatoes! I could actually taste the 'garden fresh' still in there!