Counterpressure doesn't really work (as designed anyway) unless you are filling at a higher pressure than the equilibrium pressure for the beer. You can lower this equilibrium pressure by chilling the beer as cold as it will go without freezing, you should be able to go to 28 at least.
I found counterpressure a bit finnicky with high carbed beers too. I actually have better luck with a Beer Gun (whose functionality you can approximate with standard equipment) doing everything I can to reduce foam. I go very slow, bottles and beer are very cold, I keep as much of the beer line as I can cold (in the freezer) as you will notice co2 comes out of solution quickly in the warm part. Going fast bottle to bottle (having a second person to cap) helps to keep the beer from warming much in the warm part of the line.
I was skeptical of the Beer Gun as it does not use counterpressure but for most beers it works so well I am trying to get more foam to cap on.