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.
Doesn't 86B1 specifically require an assigned score, as opposed to an artificial score? So you'd have to assign some score to the table where the infraction happened.
I guess you could assign it as a weighted score (based on the results at other tables), which would probably produce the same result as cross-IMPing.