There are two words (maybe more added to this post in the future) that I use on this blog that have different meanings from how they are typically used. One way to look at the information transfer model is as an effective theory of information, but I'm not saying it is a "successful theory of knowledge" with that phrase. That's because the words mean something a bit different.
On this blog, "information" is not meaningful knowledge (like how to do a Fourier transform or knowing the capital of Texas), but rather a measure of (reduction of) uncertainty. Flipping a fair coin once gives you one bit of information about the heads/tails state of the coin. You've reduced the uncertainty from not knowing if it was going to be heads or tails to knowing that it is exactly one of them. In economics, we use information as a measure of e.g. who buys a widget or not. Information equilibrium as used here means that the uncertainty reduced by figuring out the distribution of widgets supplied is equal to the uncertainty reduced by figuring out the distribution of demands for widgets.
On this blog, "effective" is not a synonym of "successful" or "useful" (though those definitions sometimes also apply), but rather an adjective applied to an explanation or theory focused on an effect rather than a cause. You could have an "unsuccessful effective theory". A good example is the use in the phrase "effective tax rate" where the details of a progressive tax structure, tax deductions and tax credits are combined (in physics we might say "integrated" or "integrated out" since the details disappear), leaving you with a single number. Aggregate has a similar meaning in economics. For example, the price level is an effective price that comes from combining all (or just many) of the prices in an economy.
So effective theory of information means a theory of the reduction of uncertainty associated with aggregated constituents.