If you are still interested, I would recommend going ahead with this modmod. Although many of us agree that the eras need to be reworked, there is no consensus on how to do that, so putting forward an option as a modmod is a good idea. There are a couple of things related to eras that are hard to do via a modmod, though, which is the reason why I haven't tried it yet in the space colonization modmod. If I could, I would split the future eras into four or five.
As far as classifying the techs, a starting point would be to choose X values and simply split them up. For example, the Paleolithic could be columns 1-8, Mesolithic could be columns 9-16, Neolithic 17-23, and so forth. The result shouldn't be too bad because the columns are supposed to be ordered roughly by when the techs appeared historically. Then you can move those that are clearly out of place. You might have to do some research to fix those. That's the fun part. I've put a lot of time into researching space colonization, terraforming, and such concepts, and I've learned a bunch from designing my modmod.