Law 86b1: Is this clearly favourable to one side?
I'm not sure how good such a result needs to be to qualify for "clearly favourable". The examples in the white book are more extreme than this case, so:
Result obtained by NS: 3Sx-2 500
All results for the board:
2S= 110
3H-1 -50
3Cx-1 200
3H-2 -100
2H-2 -100
2H-2 -100
2S-1 -50
4Hx-3 -500
3Sx-2 500
3Cx-2 500
3H-2 -100
3H-1 -50
3NT-1 -50
3Cx-2 500
4Hx-3 -500
2H= 110
3H-1 -50
3Cx-2 500
3H-4 -200
3H-2 -100
4H-2 -100
Do I adjust beyond the 3 Imps?

Comments
It's the top 4 or 5 results out of 22 or so, I'd call that clearly favourable. And looks like it would gain +12 or something.
Note that the laws says "clearly" and not "very", so whenever it's clear you should adjust.
When you have this many other scores, one way is to cross-IMP it and if you do that you find NS get 9.6 IMPs. You might adjust to this score, rounding up or down depending on who was at fault.