Just to answer your second question, there are "special" inventions that have a fancy border, instead of just a blue square.My main gripes with invention UI / UX is that the search function only gices a very sibtle indication of search results, and no distinction between searches that find something / searches that find nothing.
Also, to the extent that there are differances in how impactful different invention are, they are supposed to look different? if they are, I’m not noticing these differances at a glance.
I end up looking aroubd the invention trees for 10-20 minutes at a time... I suppose ill get used to where things are, but still.
On your last point, yeah it takes some time. Once you read all the inventions, you realize they are kinda grouped by function (eg in the military, there's a tree for discipline, one for supply, one for defense and one for siege) so if you know what you want, you can head in the general direction.