I hope you’re happy, I spent all day on this. After writing and running a simulation I find that the probability that any 3 lines will contain 11 or more marks is 86.96%! That isn’t even giving the other side a fighting chance. You can go up to 12 marks and still have a probability of 53.68% of winning, or an advantage of 7.36%. However, I think you have the wrong side of the empty row bet. The probability of at least one empty row is only 33.39%, better to take the other side of no empty rows. While I was at this I did lots of other probabilities and put them in a new page of keno props. Here is a list from that page of these and other good even-money bets. The good side is listed.
Even Money Keno Props
PropProbability of a Win House Edge No row will have 5 or more hits53.47%6.94% Greatest number of hits in a column will be exactly 455.2%10.4% Every row to have at least one mark66.61%33.23% Number of empty columns will not be 154.08%8.15% Top/bottom to have 9 to 11 marks56.09%12.17% 3 lines (rows and/or columns) will contain 12 or more marks53.68%7.36%