I agree, but I’m doing the most I can! Even at 12,000+ known words, I’m still finding Greek vocabulary opaque enough to need to make LingQs for the large majority of blue words I come across. I don’t consider myself particularly difficult when it comes to moving words to “known”, and yet my known word counts are dragging far behind my reading and lingqing stats.
Oh well, I’ll just keep plugging ahead I suppose. 
Im guessing Greek will lie somewhere between Russian and Spanish regarding how many known words is required to reach a level where you can more comfortably read adult fiction (with the help of LingQ). Maybe 25k words? Keep the momentum going and you’ll get there.
This is a good point. Using LingQ is very very different from using a SRS vocabulary one-word-at-a-time program. Getting 35 known words in LingQ is not the same process as drilling 35 words in an SRS software (boring, in my opinion).
Also remember that LingQ is about increasing your passive vocabulary, not your active. These “known words” are words you recognize and can identify in context via listening or reading. Only a percentage of your “known words” will be words you can easily use accurately on your own. That comes later.