This tool is free yes, and I think it's fantastic.
Wrt the sets, I understand your logic, but until you see the number of combos (side cards) it's hard to conceptualize how different countining combos in Omaha is than it is in Holdem.
For example, let's put KK back into his range... there are only 55 combos of KK (no straight) in that range I gave you whereas there are 1125 combos of TT (no straight).
Ok, I did the work:
Here is how I broke down J7, 78 and KT
edit: note on the KT... 797 is the number of combos for the range shown, 780 is the total combos of KT minus the 797 and the final value I gave to KT was all of hte 797 and 50% of the 780 to get 1187 combos, or 75% of the time he has KT he shows up to the river.
What this means is that I make sure I'm not double counting QJ with J7 or 78, etc and then I look at J7 and ask what would he need to have in his hand to get to the river and I say he needs: cc, 8, K, T, or a 9 - so if he has a pair or clubs to go with his J7 he gets to the turn and if he gets to the turn he gets to the river.
I do something similar to 78 and also KT. For TT and 99 I say he jsut gets to the river always. These are the weight columns in the next image. B100 and B50 are how often I said he would call that size bet with that holding. So for J7 I say he calls 70% of the time we bet 100 whereas he calls 100% if we bet 50 (half pot). You can tweak these numbers for sure.
Under the assumptions presented the final ev of B100 is 0.29 units of pot and B50 has an ev of 0.2389 units of pot and pot is $1280 so it's worth $372 to bet pot and $306 to bet half pot.
I'm not convinced this is the final answer as you can tweak these numbers, but I think this provides a framework to answer the question.
For the sake of completeness I did run it again with adjusted calling frequencies and got this result:
Which would indicate B50 is slightly higher EV.
The key to this though, I think, is what we need to adjust in our strategy to make him NEED to call higher with J7 and I think that means bluffing more and I think the obvious candidate is KT, but I welcome conversation on this point.