The only change I could think of - is to redirect road from Proton Ave from south to the node in the center and then to the upper green living area. It's controversial decision because the intersection in the center would be nightmare.

You may be right, I haven't had the chance to try the layout myself yet so my understanding is limited. Looking at this though it does seem to me that this level may have potential for another possible redesign, but that might be a bit optimistic.

Regarding the 15 points - I don't think so, I could not imagine saving more than, say, 40-60 tons of concrete, and to maintain a same speed would be a mini-miracle. So, around 5-7 points left there. But I may be wrong.

Agreed. Had the top-right green road been moved slightly north, at least one more small bridge could have been possible. But over-compacting might cause the whole interchange to malfunction.

In my opinion, it's essentially the same solution. All flow patterns remain unchanged, and all roads connect to the same roads. The only difference is an overpass replacing a regular crossroad with a slip road afterward. It’s a minor variation.

Very interesting solution. This seems like there's still maybe 15 points left in it - possibly with the top section being compacted a little and then the road to the top green house moving up. Either that or maybe the road from the bottom green could be made to connect earlier somehow, but that's approaching the territory of a whole new design.

There are two major flows going north: to the 52N and to the 6W.
The capacity of one lane is insufficient.

Curious if this was more efficient than merging the 2 middle lanes going to blue

It's pity that I did not screenshot my 696 points version.
The difference between it and Strawberry's 702 points lean version was striking.

This one is more a mix of both.